Originally posted by: HimizujinEternia
There's two possible explanations for that, Jing. First is that Sasuke misinterpreted Lee's monstrous strength to be Chakra. Remember, he underestimated Lee in their fight by assuming his moves were Genjutsu or Ninjutsu. The other is that he can use chakra, but he cannot mold it to perform Jutsus. It's obvious he HAS Chakra- there's no other explanation for the explosion of Chakra that occurs when he opens the later gates. I think it's more that he has no Chakra Control whatsoever.
I agree. Lee seems to be able to improve his taijutsu overall, by maybe applying chakra into his punches and kicks, as well as specials. However, he can't concentrate it to a single point, in order to perform nin and genjutsus.

As for Gai, yeah I think he can.