Tiger surges clear

US PGA champion Harrington, chasing his first victory of the year after a season of struggle as he modified his swing, started his final round at 10 under par with a three-stroke lead over world number one Woods.

But world number one Woods was in scintillating form, with an eagle and three birdies as he took a two-shot lead on 12 under, with Harrington making par on all of the first nine holes.

The Irishman had held off a back-nine charge from Woods in the third round as the American moved into second place with a five-under-par 65. Both parred the opening par four on Sunday in intensely humid 90-degree Fahrenheit heat in Ohio, before Woods piled the pressure on Harrington at the par-five second by sinking a 24-foot eagle putt to move to nine under par on the par-70, 7,400-yard South Course.

Harrington had driven into a fairway bunker at the same hole and had to lay up 75 yards short of the green. His approach to the back of the green span wickedly back off the green and his chip came up short of the pin, but the Irishman saved par with a nerveless putt from six and a half feet.

Harrington's lead had been cut to one shot and Woods pulled level at the fourth, sinking a birdie putt from 13 feet as the Irishman just missed from 17 feet.

Having parred his first four holes, Harrington found his three-shot lead had evaporated and Steve Stricker had also came into view at eight under with birdies at the fifth, ninth and 10th.

Woods' putter was as hot as the weather and when he sent down his second birdie putt in a row at the fifth, this one from 27 feet, the world number one moved to the top of the leaderboard at 11 under, already four under for the day, with Harrington recording another par to stay at 10 under.

Harrington was not without his chances and at the eighth his 14-foot birdie putt came up short by inches, but he handed the advantage to Woods at the ninth with his first significant error of the round.

Woods had sent his second shot out of the rough at the par-four hole from 179 yards to seven feet but Harrington, from the fairway, 124 yards out, sent his second shot right into a greenside bunker. The Irishman escaped from the sand to inside six feet but Woods struck another blow with a birdie putt and at the turn Woods moved into a two-shot lead at 12 under.