The Master is stronger than him, that much is obvious, but Andrew was never much of one for accepting it when he knows he's beaten. He's frightened for himself, of course; while something tells him the Master doesn't want to kill him, it's hard to say what level of injury the Time Lord would deem acceptable.

Seeing the Master distracted -- and more importantly, feeling the knife leave his throat -- Andrew twists his entire hard to one side as he shoves on the Master's arm, trying to break the Master's grip and make a run for it. He strains against the Master's hold, and then --

Andrew slips from the Master's grip, stumbling for the doors. Meanwhile, Andrew's struggles rattle the doors as he continues to fight the Master's hold on him.