As a million others have pointed out; Sakura had Chiyo on her side. Chiyo controlled her most of the fight, she had info on Sasori, she had antidotes for his poison attacks and dammit Sakura had Sasori's own grandmother fighting by her side.
How much more intel could you imagine to get before facing off an opponent?
Oh, plus, Sasori could have won. He just chose not to, in the end.
Well, yeah.
The post I quoted was saying that Asuma being one of the 12 Guardian Ninjas was only mentioned in the filler episodes and it wasn't canon, hence, the manga image.
