Stadler failed to drop a shot while carding seven birdies at Le Golf National, which will host the Ryder Cup in 2018. After turning in 3 under, he birdied four of five holes, from Nos. 10-14, and at 7 under, he leads by a shot over Germany's Marcel Siem and is two shots clear of Stephen Gallacher.
Stadler officially punched his ticket for Royal Liverpool on Wednesday, when he was one of 10 alternates added to the Open field via the Official World Golf Ranking, and he will return to the season's third major for the first time since 2008. He notched his maiden PGA Tour victory at the Waste Management Phoenix Open earlier this year and also won on the European Tour back in 2006 at the Johnnie Walker Classic.
While Stadler got off to a hot start in France, some big names struggled in the opening round, including U.S. Open champion Martin Kaymer. Kaymer, who missed the cut at the BMW International Open last week in his first start since winning at Pinehurst, opened double bogey-bogey en route to a 1-over 72 that left him eight shots back. Playing in front of partisan crowds in his native France, Victor Dubuisson struggled to a 5-over 76 after taking a triple-bogey 7 on his opening hole.
Open bids are up for grabs this week in France, as the top three players not otherwise exempt who finish in the top 10 will earn spots in the field at Royal Liverpool in two weeks' time. With Stadler now exempt, the top three players in line for those bids after one round are Siem (66), Chile's Felipe Aguilar (67) and Finland's Roope Kakko (68).