Kevin Stadler shot a three-under 68 to maintain his lead after the second round of the French Open.
The American, who shot a first-round 64, is three shots clear of home favourite Victor Riu with Germany's Marcel Siem third on five under.
Stadler hit six birdies and his halfway lead would have been greater but for a double bogey on the final hole.
There are a clutch of players on three under, including defending champion Graeme McDowell.
Also on that mark is Wales' Jamie Donaldson, who conceded he needs a big weekend if he is to make up seven shots on the leader.
"It is a tricky golf course and I wasn't quite on it today to be honest, I didn't play great by any stretch of the imagination," said Donaldson, who shot a one-over 72.
"I need a couple of really big days now and to make some putts."
Scotland's Stephen Gallagher and Scott Jamieson, and England's Mark Foster, are in the group on three under, along with Northern Ireland's Michael Hoey and Thailand's Thongchai Jaidee.
Halfway leader Stadler, who won the Phoenix Open in February and shared eighth place at the Masters in April, is making his French Open debut.
"It's just a really good golf course, greens are great and I'm certainly enjoying it so far," he said.