The leaders aren't pulling away. Phil is even through four, Westwood is one over. Both are 11 under for the tournament, and only two up on Choi and Couples, four on Poulter, suddenly back in it.
Tiger is six back, with plenty of time to do something. But he did not bring his best game at the start. He just missed par on 5, so he is three over for the day. Either he's going to be out of it soon or he is setting up a really fantastic comeback-within-a-comeback