Tiger Woods got off to a shaky start in search of his 15th Major as Y E Yang piled pressure on the overnight leader in the final round of the US PGA Championship.
Woods had begun the fourth round at a rain-softened Hazeltine National with a two shot lead at eight under par over Korean Yang and defending champion Padraig Harrington of Ireland.
Yang upped the ante with a birdie at the par five third and Woods folded at the par three fourth, three-putting for bogey to fall into a tie with the Korean at seven under.
Yang's time in the lead was short lived as he bogeyed the fifth, while Harrington narrowly missed birdie chances at the fifth and sixth to stay tied for second at six under.
Harrington’s challenge appeared to be all but over after he ran up a quintuple bogey eight on the par three eighth.
After finding water from the tee, the two time Open Championship winner fired his next shot into the rough from the drop zone and was soon back in the drink after getting a flyer.
After another drop it took him two chips to get on the green before holing a a six footer to fall back to one under.
Woods dropped a second shot of the day at the eighth after finding a bunker and even though Yang missed a birdie putt from inside five feet the former HSBC Champions winner was back in a tie for the lead at six under.
A third of an inch of rain had fallen overnight on the 7,674 yard, par 72 Minnesota course after Woods completed a third round 71 to close in on a record-tying fifth US PGA title.
Playing conservative, low-risk golf, the World Number One had seen his four stroke halfway lead cut in half by Yang's five under 67 and Harrington's 69.
Also within reach of Woods, winner of his last two tournaments, was Henrik Stenson of Sweden and American US Open Championship winner Lucas Glover, a further two shots in arrears at four under par with Denmark's Søren Kjeldsen and Ernie Els of South Africa at three under.
Woods was paired with Yang for the final round with Harrington partnering Ryder Cup team-mate Stenson in the penultimate group out, and also had history on his side having converted all 14 of his 54 hole Major leads into victories.
Glover made an early charge, getting to six under after birdies at the third and fifth but bogeying the sixth.
England's Lee Westwood picked up two shots to reach three under after 12 holes while Northern Ireland's Rory McIlroy rebounded from a double bogey six at the first with birdies at the third, fourth, fifth and ninth to also get to three under.
Stenson was at three under after two bogeys and a birdie in his first six holes while also four shots off the lead on the front nine were Els and Australian Brendan Jones.
Vijay Singh got off to a hot start, the two-time winner having gone backwards playing the final group with Woods on Saturday with a 75 caused by putting problems.
The Fijian resisted the temptation to revert to a belly putter as he began his final round and he promptly sank a 20 foot birdie putt at the first. Another birdie followed at the second, without the need for a putter, Singh holing out from a bunker to move to two under.
The fine run was halted, though, when he bogeyed the first par five hole of the day at the third, missing from short range.
He got one back at the sixth but bogeys at the ninth and 13th sent him to level par for the week.
Among the early finishers, Ian Poulter closed an erratic week with a level par 72, two over for the tournament, while a 73 from fellow Englishman Luke Donald ended his week at six over par.
Woods and Yang made the turn tied in the lead at six under par, three shots clear of a four-man group now including Westwood, third at last month's Open Championship, who had birdied the par four 14th, shortened to 301 yards again and made drivable.
Glover, Kjeldsen and Stenson rounded out the quartet until it became a trio with Stenson's bogey at the par four 10th.
McIlroy had also dropped a shot to two under at the 12th while Jones fell back to one under, where Graeme McDowell had reached with back to back birdies at the 15th and 16th.
Back at the tenth, Woods was handed a lucky break when his tee shot on the dog-left left par four struck a tree on the right but bounced out and came to rest in the middle of the fairway.
Glover was the next to drop away, a bogey five at the 12th taking him to two under, while McIlroy bounced back to three under with a birdie at the 14th.
McDowell slipped up at the par three 17th to return to level par but Harrington returned to the top ten at two under with a birdie at the 11th.