In-form American Hunter Mahan, Britain's Paul Casey and South African Rory Sabbatini grabbed a share of the lead at the WGC-Bridgestone Invitational on Thursday with Tiger Woods in hot pursuit.

Mahan, Casey and Sabbatini fired matching three-under-par 67s to set the first-round pace in sweltering, slick conditions at Firestone Country Club.

Woods, hunting his sixth victory here in nine appearances, opened ominously with a 68 to share fourth place with fellow Americans Mark Calcavecchia, Boo Weekley and Arron Oberholser, Briton Lee Westwood and Australian Stuart Appleby.

Mahan, who won his maiden PGA Tour title at the Travelers Championship in Connecticut six weeks ago, birdied three of the last five holes to maintain his golden run of form.

"It's exciting to play this good, to feel like I'm finally reaching my potential by playing the way I know I can," the 25-year-old Californian told reporters after covering his homeward nine in five-under 31.

"I'm just going out there and letting go. And I love this golf course. It sets up well for me."

Mahan shrugged off a double-bogey six at the 17th, his eighth hole of the day, to surge up the leaderboard.

"I wasn't really happy with myself there but, other than that, I played as good on about 17 holes as I could," he said.

Tiger factor

"My only concern is the fact that Tiger has been here forever and knows this place pretty well. Other than that, I feel very excited to play."

Firestone specialist Woods was satisfied with his opening round on one of his favourite layouts.

"I hit the ball pretty good today, just had a couple of loose ones, and my short game was decent," the 12-time major winner said after carding four birdies and two bogeys.

"I thought I had a pretty good touch on the greens. I do feel comfortable around here. I don't know what it is. This course just fits my eye and for some reason I've had some success here."

Woods, bidding for a third successive title at Firestone, said he had never seen the par-70 South Course play as fast.

"The fairways are really quick and the greens are unbelievably quick," the 31-year-old added.

"Everything above the hole you've really got to pay attention because there are a couple out there where you can putt right off the green. It doesn't take much."

British Open champion Padraig Harrington, back in action for the first time since his playoff victory at Carnoustie 11 days ago, opened with a 72.

Of the other big names in the 83-strong field, three-times major winner Ernie Els carded a 70 while Phil Mickelson and Vijay Singh battled to 74s.

(China Daily via Agencies August 4, 2007)