Arm wrestling?

Two people arm wrestle, Tim and Matt. For the most part they stay in a neutral position, with each one able to get small advantages. Tim can usually get an advantage in the beginning, when Matt bends his wrist back in a defensive mode. Tim can no longer advance. Matt can sometimes get a small advantage towards the end, before their grips slip or they just stop because neither one can win. Matt usually stops trying first as he says that it hurts to keep on going, and neither one can win anyway. Question: if Matt did not hurt or their grips would not slip.... who is more likely to win if they continued till a winner is complete?