"Just think about it. All the (two...) times she attacked somebody, she was able to use genjutsu to get close to the enemy. Against Ino this gave her a free hit. Against Zaku...let's just forget what came next. Sakura's genjutsu is some of the best among ALL genins, not just the female ones. She can use it to change the tactical situation to her advantage.
"

She didn't use genjutsu to get close to Zaku, she got hit by his shuriken and he assumed that it was genjutsu.