Graeme McDowell of Northern Ireland made the best of tough conditions to retain his French Open title by firing a 4-under 67 in the final round to win by a stroke on Sunday.
In pouring rain, McDowell made five birdies and a bogey for the lowest round of the day to finish with a 5-under 279 total.
Overnight leader Kevin Stadler made three birdies and dropped eight shots for a 76 to share second place with Thongchai Jaidee, who carded a 72.
Stadler had a chance on the last hole to become the first American to win this tournament since Barry Jaeckel in 1972, but he missed a long birdie putt.
McDowell clinched the victory when Stadler then failed to convert a par putt from three feet that would have forced a playoff.
Stadler went into the final round with a four-shot lead over Thongchai and Victor Riu. He even got a five-stroke cushion when Riu double-bogeyed the second hole by finding water off the tee.
Soon, Stadler put himself in trouble by missing short par putts on No. 4 and No. 6. He then double-bogeyed No. 7 by hooking his tee shot into the rough before missing the fairway with his second shot.
Another errant tee shot from Stadler on No. 8 gave Riu a share of the lead.
The title chase reached a climax when McDowell and Jamie Donaldson birdied respectively the 13th and 14th to join them atop the leaderboard.
McDowell sank a birdie putt from more than 20 feet on No. 16 to move three strokes clear. But Stadler made a strong charge to get back into contention, tying the defending champion with a birdie on No. 16.
Robert Karlsson placed fourth with a 281 total, one stroke clear of Donaldson and Matthew Baldwin.