American Jeff Overton, a last-minute entry in the CIMB Asia Pacific Classic in Malaysia, hit a new course record of nine-under 62 to share the half-way lead in the $6.1 million tournament.
Swede Fredrik Jacobson was tied with the American, who was yet to win on the U.S. PGA tour, for 13-under 129 at the Mines Resort and Golf Club.
The 28-year-old Overton, a member of the Ryder Cup team last year, arrived in Malaysia on Tuesday evening after a last-minute notice following the withdrawal of David Duval from the PGA and Asian Tour co-sanctioned event.
The American struggled in the heat and humidity and still with a little bit of jetlag hitting him, he was delighted after completing his round.
On the first hole, I told my caddie I didn't think I was going to make it. I'm still a little jet-lagged, he said.
I woke up at three this morning and couldn't go back to sleep. So, really, it's almost like being up forever.
Overton hit seven birdies and an eagle on the par four 15th and scorched the course with his new clubs.
A couple of weeks ago, I changed clubs. My golf has just improved so much. I finished sixth basically the first week I used them, at the McGladrey Classic, he told reporters.
I was hitting it really good but kind of struggled with my putter. Today, everything just clicked.
I think I made one putt outside eight feet. I was hitting everything stone cold, and it was a lot of fun.
Bo Van Pelt of the U.S. matched Jacobson's round of 64 to lie one shot behind the leaders.