Brandt Snedeker was two under par for the day and had increased his lead to four strokes by the midway point in the second round of the Buick Invitational in San Diego, California.
Charlie Wi, who began the day on nine under, was even par through five holes.
Snedeker, who is a rookie on the PGA Tour, is playing the much more difficult South Course. He began the day 11 under but had made two birdies through six holes.
On the third hole, he made a 40-foot birdie putt and on the par-five sixth hole, he reached the green in two shots and two-putted from 15 feet.
Tiger Woods, who is also on the South Course, was even par for his round through eight holes. He made a bogey on the second hole, but got it back with a birdie on the sixth.
Woods is making his first start of the year and trying to win his seventh consecutive PGA Tour event.
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