Tiger whimpers in Ohio

Tiger Woods' 270-week reign as world number one is well and truly under threat after he produced a miserable opening round on one of his favourite courses.

The 14-time Major winner carded a four-over-par 74 on day one of the WGC-Bridgestone Invitational to lie joint 70th on the leaderboard.

Woods managed just two birdies in a round decimated by six bogeys, including four on the front nine at Firestone Country Club in Akron, Ohio.

He was five-over after 16 - joint third-bottom of the entire field - before a birdie at the 17th.

Woods' woeful day was compounded by a superb recovery by world number two Phil Mickelson, who bounced back from two early bogeys to shoot a four-under 66.

That gave him a share of second place - alongside Graeme McDowell - which would be enough to overhaul his arch-rival at the top of the rankings unless Woods were to get his act together over the next few days.

Woods has yet to taste victory since returning from his self-imposed exile from golf following revelations about his private life.

He has previously been virtually unbeatable at Firestone, winning seven of the last 10 Bridgestone Invitationals he has played, including last year's tournament.

World number three Lee Westwood can also overhaul Woods in the rankings and is his playing partner here, but the Englishman failed to take advantage today, shooting a one-over 71.

Westwood had earlier been one under after two, three shots ahead of Woods, who bogeyed his opening two holes on the par-70 course.

Starting his round on the back nine, Masters champion Mickelson bogeyed the final two of his opening six holes, but he birdied the next and produced five more after the turn.

McDowell's birdie blitz was even more impressive, the US Open champion finishing his round with four on the spin and five in total.

That was enough to lie two shots behind clubhouse leader Bubba Watson, who shot a six-under 64.

Watson, who earned his maiden PGA tour win at the Travelers Championship just over a month ago, exploded into life on the back nine, carding four successive birdies before dropping his only shot of the round at the 15th.

Kenny Perry and Australian Adam Scott both produced bogey-free 66s to join Mickelson and McDowell on four under, one stroke clear of American quartet Chad Campbell, Sean O'Hair, Jeff Overton and Bo Van Pelt and South Africa's Retief Goosen.

Rory McIlroy, Paul Casey and Frenchman Gregory Bourdy were a shot further back, with three-time major winner Padraig Harrington carding a 69, Luke Donald and Ross Fisher 70s and Justin Rose a 71.

In-form Steve Stricker was unable to maintain the excellent start that saw him birdie three of his first six holes as he carded a 68.

The world number four last month set a PGA tour record for 54 holes on his way to winning the John Deere Classic.

Ernie Els shot a 69, while Sergio Garcia and Francesco Molinari fell back to level par after getting off to a good start.