German Marcel Siem fired his second successive 68 to move to the top of the leaderboard at the halfway stage of the French Open in Paris.
Siem has had only one European Tour victory in approaching 300 starts but is in the driving seat on six-under-par after a testing day at Le Golf National.
Siem double-bogeyed the 17th immediately after play resumed following an 80-minute thunderstorm delay, but then covered the front nine in a superb four-under 32 with birdies at the first, third, fifth and seventh.
He is one shot ahead of Sweden's Alexander Noren, who missed out on a share of the lead after bogeying the 18th following five earlier birdies - including three on the trot from the 14th - in his 67.
Denmark's Anders Hansen (68) and George Coetzee of South Africa (68) share third place on four under, but Lee Westwood (73) is back on one over after a dramatic collapse.
The world number three was in a tie for third place when he chipped in at the 10th, but he took penalty drops on three of the next five holes - once from heavy rough and twice from water - in dropping five shots.
"I got it together for the last few and I'm still not out of it," Westwood said. "If you hit it straight I think there's a low score out there."
Open champion Darren Clarke paid the price for one nightmare hole - a quadruple-bogey eight at the seventh, his third last hole - which left him with a 76 and saw him miss the cut by one shot.
His playing partner Paul Casey carded a second successive 80 and made his exit in joint-last place of the 155 players.