Tiger Woods shrugged off a knee injury and shot a six-under par 66 yesterday, keeping first-round leader David Berganio in his sights at the $4 million Pebble Beach Pro-Am in California.

Woods hyper-extended his knee in a collision with an over-zealous fan after a practice round on Wednesday, and didn't make his final decision to play until yesterday morning.

But the world's leading player went ahead with his defence of his title, picking up momentum as the day went on, finishing his round at the Spyglass Golf Club with a trio of birdies.

"I knew I'd play," he said. "There was some pain, but I'm okay."

His strong finish enabled him to get within two shots of Berganio, who shot a bogey-free 64 at Spyglass. The Buy.com Tour graduate is playing in just his 60th PGA Tour event.

Berganio was a stroke ahead of Tommy Armour and Mark Johnson and two better than Woods, Masters champion Vijay Singh of Fiji, Brad Elder and Edward Fryatt of England.

Players will rotate three rounds between Spyglass, the Poppy Hills Golf Club and the host Pebble Beach Golf Links before the cut is made. The final round will be contested at Pebble Beach.

Each foursome consists of two professional players and a pair of amateurs, including celebrities from the world of sports and entertainment.

Earlier yesterday, American Bruce Vaughan shot a seven-under-par 65 to take a one-shot lead after the first round of the Sun City Pro-Am tournament in South Africa. Lee Westwood, the defending champion, shot a 71, the same as Darren Clarke. Paul McGinley returned a 70.

Vaughan put together a bogey-free round, with five birdies and an eagle. He chipped in for that eagle from the back of the island green on the 18th.

"It was going at the right speed, so if it hadn't gone in it would have been an easy birdie. I was just trying to get it up and down," Vaughan said.