Mark Foster of England shot a 3-under 68 to share a one-stroke lead with compatriot James Morrison after the third round at the French Open on Saturday.
Foster made up for two bogeys with five birdies for a 9-under total of 204.
Overnight leader Morrison had a two-shot lead on the back nine but a double bogey on the penultimate hole and a bogey on the last saw him close with a 1-over 72.
''Poor finish really, a couple wrong choices,'' Morrison said. ''But very close either way. I could easily finish par, par, and have a three-shot lead. That's the way it goes.''
Richie Ramsay of Scotland climbed to third by carding a 68 despite bogeying his last two holes.
''There's just no margin for error really,'' said Ramsay, who won the South African Open in 2009. ''The ball is flying over a lot of water out there in the last four holes (...) It's tough. There probably is no tougher finish.''
Martin Kaymer of Germany and Frenchman Thomas Levet remained in contention, tied for fourth place, three strokes off the pace.
''I'm not dead yet,'' the 42-year-old Levet said. ''I can compete with the kids and I'm showing that today.''
The round did not start well for Morrison, who pulled his tee shot into the water for a double bogey on the second hole and surrendered the lead to Richard Green of Australia.
''3-iron on the second and I thought it was enough to get up,'' Morrison said. ''When it finished in the water, I was very, very shocked.''
But Morrison recovered by converting a short birdie putt on the sixth to join Green at the top of the leaderboard.
Morrison still led by a stroke on the last hole, but missed a 3.5-meter (12 foot) par putt to drop back into a tie with Foster for the top spot.
Foster started the round in third place, four strokes off the pace. He made three birdies in five holes to claim a share of the lead with Green and Morrison at 9-under, but bogeyed the eighth hole to slip back to third, one stroke off the lead.
''I saw the conditions were tough when I arrived here today, but I was positive with it,'' said Foster, who finished third at the BMW International Open last weekend in Munich. ''I just wanted to keep doing the same thing and I managed to do that.''
''It was really blowing out there, a lot of crosswinds which seems to be either into or down, and the course has firmed out a lot and it's tough to get the ball close.''
Green's round was marred by a nightmare on No. 7. After his tee shot landed into the rough, he then hit his second shot into some thicker vegetation and had to start from the same spot again, ending up with a quadruple bogey to slip down the leaderboard.
The Australian closed with a 76 to drop into a tie for seventh place with Bradley Dredge of Wales at 4-under overall, one stroke behind Thorbjorn Olesen of Denmark in sixth place.
Kaymer and Levet fired the rounds of the day with 67s.
The German had an eagle, three birdies and only one bogey.
''My short game was very good today, I could sink a lot of putts, and of course, that eagle on 14,'' the fourth-ranked Kaymer said. ''On 14, I had a perfect yardage for our 4-iron and hit it to 10 or 12 feet and could make the putt.
''If I'm only one or two behind going into the last four holes (on Sunday), I think I will play a little bit more aggressive, of course, to try to win and get the trophy back.''
Kaymer won the French Open in 2009.
Levet sank six birdies to claim a share of second place at one point, but a double bogey on the last hole set him back at 6-under overall.
''Just bad luck,'' said Levet, a runner-up at the British Open in 2002. ''I hit one bad shot today off the tee and that was one. I felt like I was going to fade it around just to avoid those bunkers on the right and it went like straight left.''
