The fourth day was introduced with a new guest judge: Rabian. With just the 8 teams remaining, each team selects a person to participant in the fourth day's event, which will occur in a large, aquatic dome-like sphere inside the arena. The rules for the event are explained fairly simply: a participant automatically loses when they leave the sphere and the last person remaining will be the winner, unless there are still two people left during which a five-minute time limit will be given so that both can compete for victory. when this exception occurs, the loser of the match will be awarded the least points.
Each participant dresses in swimwear and proceeds to enter the underwater sphere in the arena. When the event begins, Lucy apologizes to the other participants and summons Aquarius inside the water. Knowing what Lucy is about to do, Juvia quickly attacks with her Water Cyclone, creating a powerful whirlpool-like effect in the water that surprises everyone, even Aquarius herself. All the women in the water then go on the offensive. Using Juvia's attack to her advantage, Jenny lands a kick to Rocker's face and manages to force him out of the water. Chelia tries to use her magic against Risley, but is unsuccessful. Even Juvia attempts to force Lucy out from the water, but Lucy is able to save herself and summons both Aries and Virgo for help. Finally, Juvia uses a powerful attack in the water that sends Chelia, Jenny, and Risley out of the sphere. While distracted, Juvia is suddenly taken out of the water herself, leaving Lucy, Kyuki, and Minerva the only ones remaining. Kyuki then performs a heat attack that causes minor damages to both Lucy and Minerva, but forces Lucy out of the water ranking in third place.
The five-minute rule takes effect in the water sphere. Inside, Minerva tells Kyuki that she can force the latter out immediately, but as she finds it boring, she'll see how long Kyuki can last. She attacks Kyuki who, to Minerva's dismay, easily dodges it and counters back with Fire Wolf's Slash, which forcefully pushed Minerva out of the water three minutes before the round was over putting Minerva in last place. After the Naval Battle, the tag battles on the fourth day of the Grand Magic Games begin. The first battle is between Team Blue Pegasus and Team Quatro Puppy, with Rabbit & Ichiya V. Kotobuki from Team Blue Pegasus and Bacchus & Rocker from Team Quatro Puppy. Bacchus and Rocker look down on both of them, but Ichiya just acts calmly by saying that he was reveal Rabbit's 'handsome face'. This gets everyone excited about Rabbit's true identity, but when Rabbit's costume is removed everyone stares at him as it's face is almost the same as Ichiya's. Fairy Tail members like Natsu and Pantherlily are also shocked as it is Nichiya , the Edolas counterpart of Ichiya. Before Ichiya and Nichiya can explain about their first meeting, Bacchus starts the battle quickly by slapping Nichiya in the face, immediately taking him out of the battle. Ichiya, is shocked as he believed his Edolas counterpart to have the same battle power as and Rocker act fast as they get the chance while attacking Ichiya with Drill 'n Rock and Drunken Hanging Palm Moon Down. This makes Ichiya fall down, seemingly defeated. At the moment Ichiya falls down, he recalls how Nichiya was an Exceed who cannot fight yet still agreed to battle alongside him upon his asking. Thinking of him, Ichiya regains his strength and returns to battle, dedicated to beat his opponents. Ichiya begins to activate his Power Perfume and quickly becomes muscular and subsequently defeats Rocker and Bacchus by smashing them against a wall using Smiling Smash, shocking the crowd.
The second battle of the day is between Kagura Mikazuchi & Millianna and Lyon Vastia & Yuka Suzuki. As the battle begins, the two teams throw multiply attacks at each other until Kagura Mikazuchi uses her Archenemy whilst Millianna utilizes her NekÅsoku Tube Magic to attack Lyon Vastia, who is using his Ice-Make Magic, and Yuka Suzuki, who is currently employing his Wave Magic. The time runs out, ending the match in a draw.
The third battle of the day is between Cana Alberona & Juvia Lockser and Kyuki Hazunami & Raven Enjeru. As the battle begins, Cana quickly attacks Raven with her Shuriken Cards, but Raven quickly dodges it by doing a back flip and lands on the railing of Team Crescent Moon's baloney. Raven then casts Shadow Wolf's Roar towards Cana, who narrowly dodges it and casts Jolt Of Fate at Raven. Their battle continues as Kyuki and Juvia begin to use powerful attacks towards each other. The battle continues with only four minutes remaining, with this in mind Kyuki and Raven perform Unison Raid: Flaming Shadow Slash Attack together and as the smoke cleared, Juvia and Cana lay on the ground injured. Raven then goes over to them and begins to heal all of the injures on their bodies. Raven and Kyuki are then decleared the winners of the match.
The final battle is between Team Fairy Tail's Natsu Dragneel & Gajeel Redfox and Sting Eucliffe & Rogue Cheney. As Sting and Rogue ready themselves to go in, they immediately find themselves face-to-face with Natsu and Gajeel, respectively. Upon being hit in the face, they are sent flying back, much to the surprise of the audience. Chasing him down, Natsu lands a flaming kick on Sting and sends him across the area while Gajeel similarly knocks down Rogue. The knocked down Rogue then rolls to tackle down Gajeel. Sliding across the ground, Sting unleashes his White Dragon's Roar but Natsu narrowly dodges his laser-like beam by ducking underneath it, causing it to miss. Sting then directs his attack to Gajeel, but Gajeel dodges by bowing it. Then Rogue attacks Gajeel with his Shadow Dragon's Slash but Gajeel blocks it with his Iron Dragon's Sword, which is then used to send Rogue flying. Natsu then grabs the flying Rogue by the face and runs toward Sting, who expresses surprise that Rogue is being handled in such a way. With both Sabertooth Dragon Slayers in the same area, Natsu unleashes his Fire Dragon's Wing Attack, sending both Sabertooth Dragon Slayers flying from the blow. Much of the audience watches in shock as the two Fairy Tail Dragon Slayers dominate the Twin Dragons of Sabertooth in the battle.
As the Sabertooth Dragon Slayers acknowledge the strength of their adversaries, Natsu questions whether the two of them really beat dragons with their level of strength. Sting states they not only defeated them but killed them and claims he'll show the power they used to do it. Then both he and Rogue activate White Drive and Shadow Drive, respectively as Jiemma tells Fairy Tail it's over for them. Sting immediately attacks Natsu with his White Dragon's Punch while Rogue attacks Gajeel. Unable to grasp his enemy from the shadows, Gajeel's attacks go through Rogue's body, allowing Rogue to elbow him in the face. In the stands, the spectators note the difference in Sting and Rogue's strength since their amplification. While pounding Natsu with his fists, Sting tells the fire dragon slayer he always looked up to him and aimed to surpass him and that now is his time as he attaches a stigma to Natsu's abdomen and claims he will finally defeat him. Meanwhile, Rogue appears behind Gajeel as the latter tries to attack him, saying the shadow dragon will successfully hunt its prey. Just as he is about to land a blow, Gajeel grabs his arm and glares at him, asking what he was saying. At the same time, Natsu smiles as Sting charges at him. Just as Sting aims his punch, Natsu evades and decks the White Dragon Slayer in the face. Upon being asked how he could move, Natsu reveals the stigmata was burned away. Though acknowledging their opponents, the Fairy Tail Dragon Slayers tell them they shouldn't get carried away, with Gajeel elbowing Rogue in the chin, saying they shouldn't underestimate Fairy Tail. At the same time, Natsu punches Sting in the face, surprising the audience. Then Sting resolves to use his best move Holy Nova, unleashes the massive blast at Natsu. However, Natsu emerges relatively unhurt from the technique and grabs Sting's arm as the latter intended to attack, greatly surprising the Mages of Sabertooth as well as the commentators and audience while Rogue is similarly dealt with by Gajeel. Makarov notes the Second Origin Release as well as the Three Months of Training they went under and wonders how strong they've truly become as a result while the two continue to pound the Sabertooth Mages. Yajima then says that their levels are far too different.
The entire audience watches on as the two Mages can barely lift a finger against their opponents, an unexpected occurrence. As everyone wonders if the match will end in Fairy Tail's victory, the two Sabertooth Dragon Slayers struggle to get back to their feet. Remembering the promise he made to Lector, Sting states he cannot lose and gets to his feet as his body starts covering itself in scales while Rogue undergoes a similar transformation. Knowing what it is, numerous spectators look on as they realize Sting and Rogue have activated the Dragon Force. Upon the activation, Sting tells Rogue to stay back as he will handle Natsu and Gajeel himself. Gajeel comments that he's underestimating them but Natsu claims Sting is actually much stronger now. As he speaks, Sting quickly approaches.
In an instant, Sting nails Natsu in the face, sending him flying backwards. Gajeel attempts to hit Sting with his iron leg, but he misses and is subsequently hit in the face by a Holy Blast. Natsu then attempts to hit Sting with his Fire Dragon's Iron Fist but his attack is caught by the White Dragon Slayer and he is kicked in the stomach and tossed across the arena, hitting Gajeel and sending both flying. Sting then jumps in the air and unleashes his White Dragon's Holy Breath, shattering the floor of the arena and shocking the members of the audience as they comment on his strength. Despite the destruction of the floor, the match continues underground. Natsu claims the battle isn't over yet and unleashes his Fire Dragon's Sword Horn, shooting him into the air and hitting Sting, who is sent reeling back. As Sting turns around, he noticed Gajeel behind him, who then uses his Iron Dragon's Roar at point-blank range, sending Sting crashing down. However, he quickly recuperates, to Gajeel's shock, and unleashes his Holy Ray, hitting both Natsu and Gajeel with multiple rays of light. While Porlyusica wonders what Sting's element is, Natsu lands on his feet but is quickly punched by Sting's light-enhanced fist and is sent flying, unable to even block the punch. Gajeel is then kicked by Sting and the two dragon slayers of Fairy Tail attempt to take down their opponent with hand-to-hand combat with no luck as Sting shuts out their attempts as he remembers the promise he made to Lector. Sting thinks back to years ago, when Lector was claiming Sting killed a dragon and was bullied for saying so, with everyone calling Sting a liar as well. Though Sting attempted to shrug off the issue and tell Lector not to worry, Lector disagreed and stated that he didn't like people saying bad things about his friends. Sting then promises Lector that since dragons no longer exist, he will defeat the Mage known as Salamander in front of everyone so nobody will call Lector a liar again. Sting stands over the defeated Natsu and Gajeel, asking if Lector is watching him. Rogue, watching from above, comments that the era of the old generation dragon slayers is over while Fairy Tail Mages in the stands call for Natsu and Gajeel to get up. Sting agrees with Rogue but acknowledges Natsu and Gajeel's strength.
As the audience looks on at the battle, Chapati Lola wonders if Natsu and Gajeel are truly finished. However, the two soon get to their feet and acknowledge Sting's strength. Natsu immediately tells Sting he's learned his habits such as the timing of his attacks, his pose while defending and even his breathing rhythm, though he acknowledges the strength of Dragon Force. The supporters of Fairy Tail gleefully look on at the battle. At the same time, Natsu and Gajeel begin to argue about the position of Sting's pivot leg while attacking, resulting the former pushes the latter into a mining cart and pulls the lever, sending it away and leaving him unable to out due to motion sickness. Deciding to pay back Sting for underestimating him and Gajeel, Natsu decides to take on both Sting and Rogue reacts to Natsu's decision in angry manner, asking if he's serious. Rogue is ambivalent, stating he wishes to fight Gajeel, to which Natsu replies that he can if he defeats him. Sting reactivates his Dragon Force, saying nothing in the world exceeds it. Natsu responds enthusiastically as he blocks Sting's punch. As Sting claims he's using the power which killed a dragon, Natsu states he'll use his power to fight for the friends Sting mocked, quickly delivering a right hook to his face. At the same time, Rogue fires a Shadow Dragon's Roar at Natsu, and Natsu counters it with his Fire Dragon's Roar, creating an explosion which engulfs the area. Sting angrily claims the battle is not over yet, to which Natsu tells him to bring it, as his Fairy Tail allies watch.
With the entire audience watching him, Natsu dominates the twin dragons in battle, dodging Rogue's attack and kicking Sting's face. Subsequently beating the two of them, Natsu proceeds to punch both of them in the face, knocking them both back. The two soon meet up and together, combine their powers to unleash Unison Raid: Holy Shadow Dragon's Flash Fang. However, Natsu counters it with his Crimson Lotus: Exploding Flame Blade, completely annihilating the Unison Raid and causing a large explosion as a result. After the dust clears, Sting and Rogue fall to the ground, unable to continue the battle and Fairy Tail's team is declared the victor.
With the Naval battle over as well as the following battles, Jiemma called a guild meeting at Crocus Gardens. At Crocus Gardens, Jiemma asks Sting Eucliffe and Rogue Cheney about their loss against Natsu Dragneel and Gajeel Redfox and the 'disgrace' they brought to Sabertooth with this. Rogue admits that Natsu was just stronger, which enrages Jiemma.
The Guild Master attacks the Twin Dragons and demands that they remove their Guild Marks. However, Lector tries to defend them, stating that they can still grow stronger despite having lost. Jiemma doesn't recognize Lector and gets angrier when the Exceed shows Sabertooth's Guild Mark on his back. Upset at an animal having the mark, he attacks Lector with a blast of Magic, shocking the rest of the Guild as a giant wall of fire formed around Lector in a protective manner. The fire wall died down quickly revealing a pissed off Kyuki protectively hugging Lector and a dangerously pissed off Raven with a killer look in her eyes.