I was adding on to the post above me, not specifically ignoring Chiyo. However, although Sakura could not have won without Chiyo, simultaneously, Chiyo would not have won without Sakura. Both were needed because both are mediocre. Itachi is a genius ninja from the Uchiha clan. His Sharingan are better suited for a battle where one needs to be aware of everything going on around him. Not only that, but his Katon techniques are large-scale fire attacks that would be very well suited for the kind of arena Sakura and Chiyo fought in. Whereas Chiyo could attack from a distance but those attacks were easy to see coming and not all that powerful, and Sakura could attack with great damage but would have to be up close, Itachi could manage speed, power, and distance at once.