Louis Oosthuizen fired an 8-under 63 on Sunday to vault into first place after three rounds of the Deutsche Bank Championship, the second event of the PGA Tour Playoffs.

Oosthuizen, the 2010 British Open champion, appeared to be making a run at a round of 59 after rattling off seven consecutive birdies. That run ended at the 10th, though he actually played the remainder of his round in even par.

However, his score was still more than enough to put him into the lead heading into the final round, which takes place Monday because of the Labor Day holiday.

Oosthuizen set the 54-hole record with a score of 19-under par 194, and holds a 3-shot lead over world No. 1 Rory McIlroy. The Northern Irishman, who was the leader after the second round, carded a 4-under 67 and is second at minus-16.

Tiger Woods, the 2006 winner of this event, shot a 68 at TPC Boston and is tied for third with Dustin Johnson (65) at 13-under 200.

McIlroy began the round one shot in front of Oosthuizen, and two in front of Woods and Ryan Moore.

The 23-year-old McIlroy started well, with birdies at his first two holes that pushed his score to minus-14.

Oosthuizen, McIlroy's playing partner, also birdied the second but didn't start to pull ahead until the fourth hole. There, he sank a 7-footer to begin the run that put him into first place.

The South African managed all of his birdies mostly because of extremely accurate putting.

He drained 20-footers at Nos. 5 and 6, then knocked in a short effort at 7 thanks to a nice setup shot from the rough to the right of the green. At the next hole, a par 3, Oosthuizen resumed his long-range putting with a successful 42-foot try. He then made a 23-foot attempt at the ninth for a front-nine 29 to make the turn at minus-18.

A great approach at the 10th set up a near tap-in for another birdie.

"I went at most of the pins," Oosthuizen said. "Once I started getting birdies, making putts, I started going at the pins because my swing felt great, and after 10 holes being 8-under, you always think about getting it to 59. I didn't do anything different from there on in."

By the time he was done with that run, nobody was close to his score.

Following his opening pair of birdies, McIlroy parred nine of his next 10 holes while bogeying the other. Birdies at 11 and 12 got him to minus-15, but a bogey at the 15th put him even further behind Oosthuizen -- though he did manage to birdie two of his final three holes.

Woods had no bogeys and two birdies during his front nine, then had two birdies and a bogey on the back side. It was relatively clean golf, but not the kind of round he needed to keep pace with the leader.

Oosthuizen's early success allowed him some wiggle room going down the stretch of round three. After the 10th, he parred his next six holes before ending with a bogey-birdie sequence.

His first 10 holes could hardly have been more different from his final eight, but the round still made him the player to beat on Monday.

Not many appear to have a realistic chance of catching him, either. Ryan Moore (70) and Bryce Molder (68) share fifth place, but they are eight shots back at minus-11.

Jason Dufner (70) and Charley Hoffman (69) are tied for seventh at 10-under.

NOTES: Phil Mickelson shot a 3-under 68 and is tied for ninth at 9- under...Defending champion Webb Simpson (66) is a shot further behind, in a share of 14th at minus-8...Charl Schwartzel, the 2011 Masters champion, had the worst round Sunday, an 8-over 79. He fell from a tie for fifth to a share of 45th, at minus-1.