US Tour WGC Invitational:In-form American Hunter Mahan took early control at the WGC-Bridgestone Invitational yesterday with five-time champion Tiger Woods in hot pursuit.

Mahan, who has posted top-10 finishes in his last four PGA Tour starts, fired a three-under-par 67 to set the first-round pace in sweltering conditions at Firestone Country Club in Akron, Ohio.

The 25-year-old Californian birdied three of his last five holes to finish one stroke in front of compatriots Woods, Mark Calcavecchia and Boo Weekley, plus Australian Stuart Appleby.

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

Harrington, playing with Ryder Cup team-mate Darren Clarke and Boo Weekley, began brightly with a birdie at his third hole, Firestone's 12th, but the Dubliner followed that with three bogeys.

Clarke finished on even par after four birdies were book-ended by four bogeys.

He had begun in terrible fashion, bogeying the 10th, 13th and 16th, before getting back on track with successive birdies at the 18th and first holes and two more at the fourth and seventh before being pegged back with a finishing bogey at the ninth.

Paul McGinley also shot a two-over 72, but remarkably had only seven pars on his card. He opened with a bogey on the 10th, birdied the 12th and 13th, then took a triple bogey eight at the 677-yard 16th.

He finished his outward stretch with a birdie at the 18th, and picked up three more at the second, third and fifth holes.

But he also bogeyed the fourth and ninth and double bogeyed the sixth.

Mahan, who won his maiden PGA Tour title at the Travelers Championship in Connecticut six weeks ago, was delighted 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," he said after covering his last eight holes in five under.

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

Firestone specialist Woods, hunting his sixth victory here in nine appearances, 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."

Colin Montgomerie was left feeling confused following a "telephone number" back nine that still left him within striking distance of the first-round lead.

Montgomerie carded a one-over par 71 but the Scot's one eagle, two-birdie, two-par, four-bogey back nine scores of five, six, two, five, six, two, five, two, four left him bewildered.

"You've read my card on the back," Montgomerie said. "It's a telephone number.

"A good round, I suppose. Don't ask me how.

"There's nothing wrong with that, we'll see how we go. It's not easy out there."

The highlight of Montgomerie's round, which also included two birdies on the front nine, was his eagle on the par-four 17th, when he holed out with a seven-iron from 156 yards.

The Scot added: "I've got lots of twos over the years. There are thousands and thousands of twos, not too many eagles though."