You are tired twice over: once from the mental and magical fatigue of your first battle; and again from being wakened abruptly from sweet, gentle sleep. Even so, a brief lifetime of Sunnydale-honed supernaturally-aware instincts are telling you that if there was a noise, you'd better get up to investigate it, lest the next time you wake up be in something's stomach.
Opening one sleep-gummy eye, you glance about the room. Nothing unusual presents itself. Your single piece of luggage is standing up by the right-hand wall where you left it. Briar - her aura dimmed to the point where it's no longer a distinct ball of red light, merely a faint glow - is curled up in a tiny futon on the bedside table that doesn't have a lamp or clock radio. The noise didn't come from her, either. There are no other obvious candidates for the source of your sleep-interruption in the room. That means you can go back to sleep, right?
The thump which comes from the front room would seem to be a clear, "No."
Sighing, you push back the sheets and haul yourself out of bed as quietly as you can, hoping to avoid tipping off who- or whatever is making the noise, and also to keep from waking Briar up.
The tiny little groan coming from the tiny little futon, where a certain tiny little person has just mashed her tiny little face into a tiny little pillow, suggests that you have failed in your second objective.
"Sorry, Briar," you apologize. "Just restless again."
"If you try to run off to fight another monster, Alex, I will slay you," the fairy promises grimly. "Don't think I won't."
Warning given, Briar gets up, begins projecting something closer to her normal glow, and trails after you - yawning audibly - as you head for the door.
The scene on the other side is... well. There are two skinny, half-dressed old men with too little hair on their heads and too much growing on their chests and armpits - ew - bouncing around the room like a pair of demented superballs. One of the two is Lu-sensei, who is wearing his pajama pants and an expression of concentration as he leaps over and around the furniture, occasionally brushing bolts of fire - ! - out of the air and pulverizing small creepy-crawlies with glowing hand strikes. The intruder is no one you recognize: deeply tanned, wearing some kind of half-robe, half-pants thing with bright color patterns, like those Hawaiian shirts Cordy forbade you to ever buy or wear, on pain of torture. He's also draped in large strings of beads and other knick-knacks - some wood, some plastic, a few either glass or another sort of crystal, and others that look like bone - which rattle as he moves about the room in brief bursts of teleportation whenever Lu-sensei gets too close.
"...it is too damn early for this crap," Briar moans.
You sort of agree with her.
At a glance, Lu-sensei appears to have things well in hand. At the very least, he's simply in the zone, whereas his opponent is visibly sweating and starting to breathe hard. Between his age and his ability to teleport three - make that four - times since you peeked into the room, you're guessing this guy must be Arrogante's summoner; flunkies can't teleport that often or that accurately, even at short range. The fact that fighting Lu-sensei is clearly taking a toll on the intruder is really not all that surprising. People who summon big nasty monsters like Arrogante to do their bidding frequently do so because they, themselves, are not big nasty monsters, and given what you know of the advantages and limitations of Earth's major magical traditions... yeah, you can see how a guy who could use ritual and external power sources to call up an overgrown cephalopod that you had to work to kill might end up struggling in close-quarters combat with your crazy old master.