Sand Grainy Death
Summary: In which the plot armor is suspiciously absent and the plot does not save the characters from their own stupidity.
There was just no way that Sasuke could defeat Gaara.
Still, he trained his butt off in an effort to grow strong enough to match Lee's speed.
Unfortunately for him, a single month of training could never match the years Lee had spent improving his physical body until he could move at the speed he did.
Kakashi, in hindsight, thought that he really, really should've just told Sasuke to fold when he could. Maybe give a good showing, toss a few jutsu around, and then just quit before he died. As it was, he'd caused one of his students' death because he'd been too focused on training Sasuke to survive his fight with Gaara to actually do the sensible thing.
Admittedly, it probably wouldn't have worked, but he could always just forcefully withdraw Sasuke.
Because he had been proud of his student's achievements in a month, however, he waited until Sasuke tried to use the Chidori to assassinate Gaara. Unfortunately, all that happened was that Sasuke ran straight into a sand spike that impaled and immediately killed him.
And then Naruto went four tails all at once, killed Gaara, and then there was chaos.