Louis Oosthuizen matched the course record on Friday with his 9-under 63 and that helped him grab a 5-stroke lead after two rounds of the WGC - HSBC Champions.
Oosthuizen finished 36 holes at 16-under-par 128. His total of 128 set the tournament's 36-hole record by four strokes. David Howell and Nick Dougherty set the old mark of 132 in 2005.
The 16-under total is a World Golf Championship record, besting the mark of 15-under that Tiger Woods set at the 2000 Bridgestone Invitational and 2006 Cadillac Championship.
Adam Scott, who shared the first-round lead with Oosthuizen, carded a 4-under 68 to dip into a share of second place. He was joined at minus-11 by British Open champion Ernie Els, who matched Oosthuizen's 63 on Friday.
Jason Dufner (66) and Shane Lowry (68) are tied for fourth at 10-under-par 134, while Dustin Johnson (68) and Phil Mickelson (69) are one back at minus-9 on the Olazabal Course at Mission Hills.
Oosthuizen, the 2010 British Open champion, stumbled to a bogey on the second, but erased that mistake with a birdie on No. 3. He came back with a birdie on the fifth and an eagle on the par-5 seventh to get to 10-under.
The South African holed a birdie effort from off the green on the eighth. That gave him a share of the lead alongside Scott at minus-11.
Oosthuizen, the Masters runner-up, made it two birdies in a row as he chipped his third on the par-5 ninth within a foot. Around the turn, he kept rolling.
He drained a long birdie putt on the 10th and came right back with a kick-in birdie on the par-5 11th. Those birdies gave Oosthuizen a 3-shot lead.
Oosthuizen settled in with three pars in a row from the 12th. He sank a 4-foot birdie try at 15 and made it two in a row with a 6-foot birdie putt at 16. He parred out to end there.
"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 stated.
"I played the par-5s really well, and I think I was 6-under on them today. 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."
Scott, in the group behind Oosthuizen, was on fire early as he poured in three consecutive birdie efforts from the third. He climbed to 11-under with a birdie on No. 7.
The Australian birdied the 11th for the second day in a row, but stumbled to bogeys at 12 and 13. He got those shots back thanks to birdies on 15 and 16, but another bogey at 17 left him five back.
Els had a tremendous front nine that started with three consecutive birdies to open his round. After a par on No. 4, he once again birdied three in a row from the fifth to jump to minus-8.
The 4-time major champion birdied the ninth to shoot 7-under 29 on the front side. That gave Els a chance to shoot 59 with two more par-5s on the back nine.
However, Els cooled off. His only birdies on the back nine came at the 12th and 14th. They got him to 11-under and he finished his round with four pars in a row to finish 36 holes bogey free.
"That's pretty nice scoring. Obviously, I had a good start and all that, but I wish I could always play like that," Els said. "That number was crossing my mind. I just didn't quite make the putts coming in."
NOTES: Oosthuizen has birdied or eagled every par-5 through two rounds. He has played those 10 holes in 11-under par ... Along with his four major championships, Els also has two WGC titles to his credit ... Defending champion Martin Kaymer carded a 3-under 69 and is tied for 12th at minus-7 through two rounds.