If Sakura would have fought Sasori alone then that reference would have been valid, but we all know that she had a huge assistance from Chiyo. Big difference fighting someone one on one than with backup. Something to consider...
Fact is, she was keeping her cool in a fight against much stronger opponent. Teamwork was the key to win this, but Sakura has played her role well.
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-> From that point Chiyo wasnt controlling her moves. Few links:
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-> Chiyo knows what shes talking about.
Sakura has a weak point, and that point is Sasuke. Then again, even much more powerful and experienced shinobis have point like that. Remember when Orochimaru was leaving Konoha? Hiruzen couldnt bring himself to kill him, even though he knew very well that Orochimaru was responsible of killing several villages civilians and shinobis, Oro even killed two ANBUs on his eyes. And we are talking about Hiruzen here, the guys who was Konohas Hokage for years.
But saying that Sakura has no guts or that Hinatas spirit is much stronger is simply unfair. Even Sasori aknowledged her.