Nicolas Colsaerts saw his advantage trimmed to one shot as the famous back nine at Le Golf National promised a thriling finish to the Amundi Open de France.
The big hitting Belgian had started the day with a three shot advantage but he turned in 37 as the rain fell to slip to 12 under and open the door to the field.
Playing partner George Coetzee picked up a shot on the front nine to sit one back, with Dane Joachim B Hansen at nine under.
German Martin Kaymer, Dutchman Joost Luiten, Ireland's Gavin Moynihan and Scot Richie Ramsay were four off the lead.
Colsaerts is looking for a first win in seven years and five months as he looks to keep his playing privileges, while Moynihan is also in a battle to keep his card.
Colsaerts' lead was quickly extended to five as he picked up a shot on the first with an approach to two feet, with nearest overnight contender Coetzee surrendering a bogey after finding water off the tee.
A bogey on the second after a poor chip dropped the leader back to 13 under and third member of the final group Jamie Donaldson found the water twice for a quintuple bogey eight as his chances quickly disappeared.
Colsaerts took advantage of the par five third after getting a fortunate bounce from the trees and getting up and down, but the lead stayed at four as Coetzee holed from 18 feet after finding a greenside bunker with his second.
A long three putt on the fifth brought the second bogey of the day for Colsaerts and when he failed to get up and down from the side of the next, the advantage was just two.
Coetzee almost found the water with his tee shot at the par five ninth and had to play his second with his feet in the water but, when he rolled a very long putt up the slope and in from off the green, the lead was down to one.
Hansen had made the most of the third and while he gave the shot back on the next, a smart approach to the sixth meant he was just three back.
Luiten was making the move from back in the field, with gains on the third, fifth, ninth, 11th and 14th moving him to eight under.
Ramsay birdied the fourth but dropped a shot on the seventh in his first ten holes, while playing partner Kaymer birdied the first and fifth but dropped a shot on the fourth.
Moynihan had bogeys on the fourth and seventh but hit back on the eighth and ninth in his first ten holes.
England's Steven Brown was seven under, a shot clear of Thomas Detry, Kurt Kitayama, Hugo Leon and Chris Paisley.