While I can't easily find and good pictures on the Naruto wiki, I remember that Tsunade's weakened state has been shown at least twice. The first time was in the first part of the series, after the battle with Orochimaru and Kabuto. She used up so much chakra that her age transformation jutsu dispelled and showed her true age. The second time I can recall was after the battle with Pain in Konoha. If I remember correctly, she was so exhausted from that battle that she became bedridden and almost lost her position as Hokage. Breaking the seal in her forhead just gives her access to great amount of stored chakra. But she usually has little left after using it, since it's a trump card.
I actually do have a favorite Sannin, I think they're all pretty amazing in their own rights.
I've even gain some more respect for Orochimaru lately. :p
Manga 629 leaks
Uh-oh, Naruto's empty light just came on.
But what's with the faces of the other Tailed-beasts in that one panel?
And is that Pain's eyes in the next panel?
These panels don't make much sense to me... >3>
Wow, the Ten-tails is transforming as much as Freeza...
And then Kakashi and Obito have their heart to..hole, talk. :p
Rin being forced to become the Three-tails' Jinchuriki was a twist I didn't expect.