GERMAN Martin Kaymer sealed a Ryder Cup debut in the grandest manner possible on Sunday night - by winning the final major of the season after a three-hole play-off with left-hander Bubba Watson.

But the abiding memory of the 2010 United States PGA Championship at Whistling Straits - one in which 21-year-old Rory McIlroy came joint third, just as he did last year and in The Open last month - will be of Watson's fellow American Dustin Johnson rubbing out a bogey five on the final hole and inserting a seven instead.

Johnson, the player who blew the US Open in June with a closing 82, was one ahead with one to play and thought when he missed a six-foot par putt that another chance was still to come in the play-off.

Instead he was penalised two strokes after it was ruled he had grounded his club on the sand before hitting his second shot.

The course on the banks of Lake Michigan has over 1,000 bunkers, but many of them are not easily defined, so the rules of play for the week are that "all areas... designed and built as sand bunkers will be played as bunkers (hazards), whether or not they have been raked."

As Johnson was left to reflect on another crushing disappointment, Kaymer and Watson went at it alone after both finished on the 11-under-par total of 277, one ahead of McIlroy and Zach Johnson.

Watson struck first by pitching to two feet at the 10th, but Kaymer responded with a 15-foot putt on the short 17th.

The decisive moment came when Watson then struck his second into the water when they returned to the 18th.

He did hit the flag with a chip, but could do no better than a double-bogey six and 25-year-old Kaymer, having laid up from the rough, won with a bogey five.

Kaymer's victory makes it two European wins in the last three majors following Graeme McDowell's US Open triumph.

"I was nervous in the regular round, but it the play-off it was strange - I felt very calm, very confident," commented Kaymer.

"It's just amazing. I don't realise what has just happened - I just won my first major and I am just on Tour for four years. I have goosebumps."

McIlroy was hoping to utter such words, of course, but after taking a share of the lead with a birdie on the 14th he bogeyed the next and then missed a 15-foot birdie putt at the last to come up one short.

What happened to Johnson was rough on the 26-year-old and he was still not convinced afterwards that the penalty was deserved.

There were boos from the crowd when it was announced, and Johnson commented: "It never crossed my mind I was in a sand trap.

"The only worse thing that could have happened was if I made that putt (to 'win').

"I just thought I was on a piece of dirt the crowd had trampled down.

"Obviously I know the rules - you can't ground the club in a bunker - but I guess it's one situation where I should have looked at a rulesheet.

"The official said the whole course is a bunker. It's up to them. If it was up to me I would not have thought I was in a bunker."

Meanwhile, Kaymer's performance knocked Luke Donald out of an automatic qualifying place on the Ryder Cup table and left him needing a wild card along with Padraig Harrington.

For Harrington that was also because Paul Casey's surge into joint 12th spot was just enough to lift him above the Dubliner into the ninth and last qualifying spot by less than £1,000.

However, there are two weeks left and Casey could himself be overtaken - a possibility he has left open by opting to stay in America rather than going back for the race-ending Johnnie Walker Championship at Gleneagles.

McIlroy said: "It was just a weird day. I got a good putt on 14, but I missed one on 15, which was quite disappointing.

"I'll take the positives from it. It wasn't the result I wanted, but it's a learning experience."

Casey shared 12th with, amongst others, fellow Englishman Simon Dyson and Masters champion Phil Mickelson.

Dyson has kept alive his Ryder Cup hopes in the process, but Mickelson did not do enough to topple Tiger Woods (28th on two under) from the world number one spot.

If Johnson was the heartbreak story, the nightmare one belonged to overnight leader Nick Watney.

There were echoes of his playing Johnson at Pebble Beach as he double-bogeyed the first, triple bogeyed the short seventh and crashed to an 81.

It cost him an automatic Ryder Cup place. Johnson did at least have that as consolation, as did Watson.

The two of them knocked Anthony Kim and Lucas Glover out of the top eight. Captain Corey Pavin names his four wild cards - Woods and Kim included in all probability - on September 7.