Phil Mickelson shoots 4-under 68

HUMBLE, Texas -- Phil Mickelson turned in a bogey-free, 4-under-par 68 in the first round of the Houston Open on Thursday, showing no effects of the muscle pull that forced him to withdraw from last week's Texas Open.

The five-time major winner, who practiced at Augusta National for two days this week in advance of next week's Masters, was two shots behind early leaders Keegan Bradley and Matt Kuchar; both finished at 6-under 66. J.B. Holmes was also at 6 under after 17 holes.

Mickelson and Bradley were part of a threesome with Webb Simpson, who also finished at 4 under. All three players navigated the 7,441-yard Golf Club of Houston layout without a bogey.

Stewart Cink finished his morning round with a 5-under 67.