Louis Oosthuizen smashed Tiger Woods' 36-hole World Golf Championship record on Friday as he leaped into the halfway lead at the WGC-HSBC Champions event in China.
South Africa's world No. 11 carded a course record nine-under-par 63 at the Mission Hills Golf Club in Shenzen to move five shots clear in the $7 million event.
The 2010 British Open champion went to 16 under par after two rounds, bettering Woods' efforts at the 2000 Bridgestone Invitational and the 2006 Cadillac Championship.
Oosthuizen started the day tied for the lead with world No. 6 Adam Scott but moved clear of the Australian, who was joined in a tie for second by Ernie Els -- the man who took advantage of his final-day collapse to win July's British Open.
Four-time major champion Els matched his compatriot Oosthuizen with a 63 on his return from an ankle injury.
Oosthuizen held a five-stroke lead after two rounds of the British Open two years ago, before going on to win by seven shots at St. Andrews for his first major triumph.
"Scoreboard-wise, it's probably the same," the 30-year-old told the European Tour's website. "Looking at the leaderboard, there's so many great players up there. Like I said, it's far from over. It was probably the same at the Open.
"With this tournament I'm in a great position to win it, but it's not even crossed my mind at the moment. There's still a lot of golf to be played, and I need to put myself in a great position going down the back nine on Sunday."
Oosthuizen's landmark round included an eagle at the par-five seventh hole and eight birdies.
"I played the par fives really well, and I think I was six under on them today," he said.
"The rest was down to putting really well. I gave myself a lot of opportunities for birdie, and hitting fairways, hitting greens, and if you make the putts, you shoot a low number.
"You get those days where if you hit it well, you leave yourself in a decent spot for a chip-and-putt for a birdie on the par fives."
Els' ankle injury ruled him out of last week's Grand Slam of Golf, an event which pits the year's four major winners against each other. The 43-year-old's replacement Padraig Harrington took home the $600,000 winner's check.
"I obviously had a good start and all of that, but I wish I can always play like that," former world No. 1 Els said after recording a 29 on the first nine holes.
"I'm just glad to be here; after going down on the tennis court two weeks ago to stand here and shoot 63 is quite a bonus."
Portugal Masters winner Shane Lowry (68) was nine under, tied for fourth with American Jason Dufner (66).
One shot further back were Dufner's U.S. Ryder Cup teammates Dustin Johnson (68) and Phil Mickelson (69), who won this event on two previous occasions when it was held in Shanghai.
Former world No. 1 Luke Donald, a member of the European team which registered a dramatic victory over the U.S. at Medinah last month, was eight under after carding a second consecutive 68.
His European teammates Peter Hanson, Martin Kaymer (69), Lee Westwood (67) and Ian Poulter (68) were in a group tied for 12th on seven under.
Sweden's Hanson, who is second in the Race To Dubai standings behind the absent world No. 1 Rory McIlroy, fell down the field as he followed up his opening 66 with a 71.