Harrington keeps Tiger on his toes

Woods got his third round under way at seven under par in Minnesota in the knowledge he had not lost the eight major championships he had led at the halfway stage and with a four-shot overnight lead the world number one had threatened to turn the final major of the year into a procession.

Defending champion Harrington had reeled in Woods' lead as the final groups neared the clubhouse, but having been caught, the 14-time major winner was sparked out of a nine-hole run of pars with a birdie at the 14th.

Then Harrington bogeyed the 18th for a third-round, three-under-par 69 and Woods returned to grind mode and parred his way home for a one-under 71, at eight under a stroke ahead of the Irishman and South Korea's YE Yang, his 67 the low score of the day.

Henrik Stenson of Sweden and US Open champion Lucas Glover will start the final round at four under after rounds of 68 and 71 respectively with Denmark's Soren Kjeldsen and Ernie Els of South Africa at three under, both having shot 70s.

"I was just trying to be very patient out there," Woods said.

"The golf was playing a little more difficult and I had the lead so I played conservatively. I didn't give myself a lot of looks and the one putt I missed was the three-putt (at the fourth) so other than that it was a really good, solid day."

Harrington was left a little deflated after his closing bogey.

"It was a little disappointing," he said.

"Sometimes when you get off to a shaky start and make a few pars you do feel better for it. Then I did start playing well and I holed a few putts and I was feeling good about things. Then at the end I got a flyer out of the rough and it was a disappointing way to finish."