Her knee lands right in his stomach, a lot harder than he thought she was capable of. Vegeta's been hit a lot harder than this, but it's still pretty hard considering. He bends over slightly from the impact, feeling a bit of air knocked right out of him. His own hands go up in a guard, expecting a hook of some sort or anything at all to continue the assault. She'd gotten him but he won't let that happen again if he can help it.

He also feels that it's almost that time to make her go on the defensive.