Grégory Havret overcame a second consecutive double bogey at the 15th to maintain his narrow advantage at the Johnnie Walker Championship at Gleneagles.
The Frenchman shot a 69 to move to 11 under par at Gleneagles, enough to give him a one shot advantage over Anthony Wall.
By the time Havret started his round he had been caught at the top of the leaderboard but jumped into a two-stroke lead with an eagle on the 516 yard second.
He then parred the next six holes before a four on the par five ninth took him to three under for the day.
A birdie-bogey-birdie run through the 12th, 13th and 14th strengthened Havret’s position but then he took six shots on the par four 15th for the second day running.
An instant reply at 16 saw him pull a stroke back and when he registered a four on the par five 18th Havret ensured he would be the man to catch on the final day.
Havret said: "It's going to be a big hunt tomorrow, especially with those Ryder Cup guys. I heard the weather will be bad, but we'll see. It's going to be quite open, for sure.
"I was quite upset obviously after the 15th, but I don't blame myself. It's not an easy hole."
England’s Wall had earlier stormed into contention by matching the best round of the week - an eight under par 65 - to climb to ten under with a birdie blitz.
Wall’s round included six consecutive birdies from the 11th as he completed the back nine in an electrifying 31.
Back-to-back birdies got Wall off to the perfect start but he then dropped a shot at the fifth.
He atoned with a three at the par four eighth, only to bogey the tenth, before storming through the last eight holes with seven birdies - only the par three 17th prevented him recording eight straight birdies.
Five players are battling behind the top two a shot further back in a tie for third.
Argentina’s Ricardo Gonzalez compiled a second straight round of 67 and has now not carded a bogey in his last 36 holes.
An eagle at the par five 12th was the highlight of his round.
Denmark’s Søren Hansen is also nine under - and all but assured of a Ryder Cup place - following a five under par round of 68, which featured six birdies.
One player already guaranteed a spot in Nick Faldo’s European side is Lee Westwood and he produced a 32 on the way in, including a two at the par four 14th, to move into a share of third place.
England’s David Howell recovered from bogeys at the tenth and 13th to birdie four of his last five holes, and German Marcel Siem completes the group having birdied 12, 13 and 14 on his way to a round of 66.