Wouldn't be that easy, having Ichigo defeat Grimmjow in that eleven seconds of off-screen fighting.

I, for one, am hoping that Kurosaki Isshin flashes in to take the next hit for Ichigo and proceed to beat the crap out of the ex-Espada, zanpakutou released state and all. Then they'll indulge in a heart-warming moment in which all is revealed to Ichigo, and he and his father develop a deep, mutual respect for each other as they team up to fight off the rest of the Arrancar.