Saint-Quentin-en-Yvelines - Thongchai Jaidee and Finn Mikko Ilonen both carded under-par second rounds on Friday to take a share of the lead in the 100th French Open at Golf National.
The experienced Thongchai had a topsy-turvy day with three bogeys and four birdies for a 70, while Ilonen joined him at the top of the leaderboard after firing an excellent three-under-par 68.
Earlier, defending champion Bernd Wiesberger, starting on the back nine, soared into a four-shot lead with five birdies in his first eight holes, only for a triple bogey at the 18th to halt his momentum.
Two closing bogeys left him a stroke behind Thongchai, Ilonen and afternoon starter Lucas Bjerregaard of Denmark.
It was another bad day for Masters champion Danny Willett, who looks set to miss the cut, although playing partner Lee Westwood was three under par for his second nine holes to secure a place for the weekend.
Thongchai backed up his opening 67 with a solid second day.
A fine iron shot into the ninth green, his last hole, set up a simple birdie to reach five under par for the tournament.
The world number 262 Ilonen, who was ranked in the top 50 less than two years ago but has struggled with injury and loss of form, looked back to his best in France.
The five-time European Tour winner had five birdies in his round, with an excellent par save at 17 helping him stay on five under.
Dane Anders Hansen, who only came out of retirement last week at the BMW International Open, carded a three-under-par 68 to move into a tie for fourth place alongside Wiesberger and big-hitting Belgian Nicolas Colsaerts.
Westwood fought back from a difficult start with three consecutive birdies on the back nine en route to a second-round 70.
After starting on the 10th, the 43-year-old was five over par for the tournament through nine holes, but a good downhill birdie putt on the par-three second hole got his week belatedly up and running.
The Englishman, who collapsed in the final round of the US Open at Oakmont less than a fortnight ago, now looks all but certain to make the cut on two over par.
There was no such luck for Willett, as the world number nine struggled to find any consistency with his swing and missed a succession of birdie efforts on the greens.
A second round score of 72 leaves him on five over, three strokes below the projected cut line and needing plenty of favours from the afternoon starters to make the weekend.
The 2013 and 2014 winner Graeme McDowell will miss the cut by a distance.
The 2010 US Open champion endured a nightmare first-round 80 on Thursday, and followed that up with another over-par effort to end up on 11 over par.