He is shoved off, as Megatron wanted and along with the elbow to the face doesn't really manage to do much.

Evidently, the damage is starting to take it's toll. Strong as he is, Sentinel isn't a .1%er and can't take as much as Megatron can. Luckily enough, Megatron isn't underneath him when he hacks up a load of energon and a few bits of metal. Pity, really, Sentinel thinks. It's disgusting, but it could have temporarily blinded him.

Despite the space giving him ample opportunity to strike back, he can't.