FINAL-ROUND LEADERBOARD: (GB & Ire unless stated)
-13 * M Kaymer (Ger), L Westwood * Kaymer won sudden-death play-off
-10 I Poulter -9 A Hansen (Den), P Hanson (Swe)
Selected others:-9 K Ferrie, P Waring -5 C Montgomerie, R Echenique (Arg) -4 N Dougherty -2 D Clarke
Kaymer also beat Westwood in Abu Dhabi last year
German Martin Kaymer beat England's Lee Westwood in a play-off to claim victory in the French Open, near Paris.
Westwood produced a final-round 65 as he shot seven birdies and a bogey to take the clubhouse lead on 13 under.
Kaymer, 25, kept his nerve to par the final three holes for a 68 and send the tournament into a play-off.
The pair went to the 18th for the first hole in a sudden death shoot-out but, while Kaymer missed the water, Westwood did not and had to settle for second.
Kaymer's second shot on the 18th fell just on the edge of the water around the green, while Westwood's effort went into the hazard.
The German, the European Tour Rookie of the Year in 2007, sank a lengthy putt to confirm victory and deny Westwood a first victory since September 2007.
You can't judge the week by that and I certainly can't be disappointed by anything after the way I played today
Westwood, who was runner-up to Kaymer in Abu Dhabi at the start of last year, has also now lost three play-offs since his last win but showed he is in good form ahead of the Open, which starts on 16 July.
"Martin's ball has carried the water by a foot and mine must have went in by a foot. That's the chance you take in play-offs," said Westwood.
"You can't judge the week by that and I certainly can't be disappointed by anything after the way I played today.
"I was delighted with my putting today. I had 31 putts for the first three rounds and that's just not good enough, but I putted a lot better today and that's just what I need to do.
"If I can carry that on then I will be winning events by a couple of shots and not going to play-offs. It is a good time to start playing well."
Kaymer became the first German to win the tournament since Bernhard Langer 25 years ago and could have wrapped up victory sooner had he taken birdie chances at the 16th and 17th.
"This is obviously very special for me. I had some good chances, but finally I won it, so it's good," said Kaymer.
Ian Poulter had seemed set to challenge for the lead before going into the water at the 15th.
The Englishman claimed third on 10 under but blamed a photographer for his mistake and was furious at the end, saying he would take the event off his schedule next year.
Overnight leader Rafa Echenique, of Argentina, had a nightmare on the final few holes as he twice found the water and his 77 saw him plunge down the leaderboard and finish on five under.
He was joined on that score by Scotland's Colin Montgomerie, who is still searching for a top-10 finish since finishing runner-up in the French Open last year.
Montgomerie shot an eventful par final round, including seven birdies and seven dropped shots.
There was also a spot on offer in the Open for somebody who had not qualified as long as they could finish in the top five.
English pair Kenneth Ferrie and Paul Waring came agonisingly close only to miss out by just one shot.