Sasuke runs after Itachi, like canon. so Kakashi tricks Gai into going after him.
Kakashi: Gai! Let us have a youthful challenge over which one of us can catch my youthful subordinate first!
Gai: Yosh! *jumps through the wall after Sasuke*
Asuma: Aren't you basically bedridden?
Kakashi: I suppose that means he's going to win then. Good thing I speak Youth."