Inspired KJ Choi takes initiative in Pennsylvania

Choi managed an unexceptional 69 on Thursday, but was in inspired form yesterday as he matched the course record, with four straight birdies on the opening nine setting him on his way.

He made the turn in 30 and, although he bogeyed the 11th, back-to-back birdies on the 15th and 16th ensured he finished his round in top spot.

Choi's passage to the top was eased by struggles for overnight leader Adam Scott, who could only manage a one-over-par 71, his afternoon marred by a double bogey on the 14th and bogeys on the third and 17th.

Choi enjoyed a two-shot lead over Chris Riley, who went around in 66, and Charlie Wi, who reached the 11th at four under on the day.

Charles Howell and Bryce Molder were both one shot further back.

Joe Ogilvie, Jhonattan Vegas and Kyle Stanley, who had all been one shot behind Scott overnight, likewise struggled to make an impact yesterday, as they were all on level par at the midway stage.

Scott, who had fired a four-under-par 66 in his opening round on Thursday, has tournament host Tiger Woods' regular caddie on his bag. "It's been fun to have (Steve Williams] on the bag for a couple of weeks," said the Australian. "I've learned some things. He knows how to manage his way around the golf course. He's got a wealth of knowledge and he's been a great help."

Williams is on loan to Scott with Woods' permission but is expected to return to his long-time employer after the American recovers from his leg injuries and resumes playing.

Woods said this week he has no timetable for his comeback from left knee and Achilles tendon problems. If he can't play in The Open in two weeks, Scott said he expects Williams to caddie for him at Royal St George's.