SHENZHEN, China -- Louis Oosthuizen shot a blistering 9-under 63 Friday to set a new 36-hole World Golf Championship record and open up a commanding five-stroke lead at the WGC-HSBC Champions.
The 2010 British Open champion, the co-leader overnight, had eight birdies and an eagle to offset one bogey at Mission Hills.
He sits at 16-under 128 overall, the best 36-hole round score in the WGC history, bettering the 15-under marks set by Tiger Woods at the 2000 Bridgestone Invitational and the 2006 Cadillac Championship.
His fellow South African and reigning British Open champion Ernie Els jumped from 19th place after the opening round into a share of second with Australian Adam Scott at 11 under.
Els made seven birdies on the front nine to card a 29 -- the lowest nine-hole score of the day -- before also finishing his round with a 63.
Shane Lowry and Jason Dufner were in fourth place, six strokes behind the leader at 10 under. Phil Mickelson double-bogeyed his final hole to fall into a share of sixth with Dustin Johnson after moving into contention with two eagles on the front nine.
Oosthuizen again made the most of the five par-5 holes on the Olazabal Course, birdieing four and making eagle on the 566-yard seventh. He birdied all five par 5s in the first round on Thursday.
The South African nearly had a second eagle on Friday, too. After hitting his second shot into a bunker on the par-5 ninth, he hit a difficult chip shot over a ridge and onto the green that rolled 15 feet and missed the pin by inches.
"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 5s," he said. "I think I can reach all of them, which, you know, makes it easy."
Oosthuizen is having one of his best years on tour, with two titles and a runner-up finish to Bubba Watson after a playoff at The Masters. He says the highlight, however, was a single shot -- the albatross, or double eagle, which he hit on the par-5 second hole in the final round at Augusta National.
He's not expecting to repeat that feat at Mission Hills, but he is hoping he can keep hitting well off the tee on the long holes to bag as many birdies as he can.
"I've just been playing really, really solid to shoot low numbers," he said. "I'm in a great position to win it, but it's not even crossed my mind at the moment."
If anyone can catch him, it might be Els, who came from six strokes down at the turn in the final round of the British Open to capture his fourth career major.
He's happy to be at Mission Hills after falling and injuring his ankle during a tennis match two weeks ago. He said the ankle is still swollen and a little painful, but he's able to hit and walk on it.
"I feel it, but it's allright. You know, what do they say, be aware of the injured golfer," he said with a wry smile.
Mickelson, a two-time HSBC Champions winner, played a superb front nine with two eagles and two birdies to move into a share of second place with Scott at the turn.
But on the 18th he barely cleared the lake and landed in the rough on a steep slope next to the green. Balanced awkwardly with one foot on a rock and the other on the hill, he missed the ball completely with his first swing. He popped it onto the green with his second attempt, but then missed a 10-foot putt for bogey.
"It's disappointing finishing with a double, but I played pretty well for the most part throughout the first 12, 13 holes," he said. "I just played a little sloppy coming in."
Scott, the co-leader with Oosthuizen after the first round, made four birdies to keep pace on the front nine before blundering an opportunity for birdie on the par-5 ninth, which he had eagled the day before.
After positioning himself well with a deep second shot that nearly reached the green, the Australian left his chip shot short, setting up a difficult 10-foot putt. He pulled the putt wide by inches and had to settle for par.
Scott's struggles continued on the back nine with three bogeys to go along with his three birdies. Still, he believes he can make up ground on Oosthuizen over the weekend.
"Five shots is just a couple of holes to get back," he said. "There are eagle chances and there's also a lot of trouble, so it can all turn around quickly."
Watson and Peter Hanson and fell off the pace after trailing by one coming into the day. Hanson slipped to 12th place after carding a 71 and Watson plummeted to 17th after triple-bogeying the tricky par-5 15th and finishing with a 72.