Stadler overcame a double bogey on the par-5 ninth, notching six total birdies to remain atop the leaderboard after opening with a 64. At 10 under, his closest pursuer is France's Victor Riu at 7 under, while Germany's Marcel Siem is in third place, five shots behind Stadler.
While Stadler claimed his first PGA Tour victory earlier this season at the Waste Management Phoenix Open, his first win on a major tour came in 2006, when he won the Johnnie Walker Classic. He is using this week to prepare for the Open Championship, as the 34-year-old will return to the season's third major for the first time since 2008.
Several notable names made moved up the standings Friday, including U.S. Open champion Martin Kaymer, who shot a 3-under 68. At 2 under, he enters the weekend tied for 12th, eight shots back after missing the cut at the BMW International Open last week. Crowd favorite Victor Dubuisson bounced back to card a 68 after an opening 76 to ensure he plays the weekend, while Graeme McDowell will begin the third round tied for fourth after rounds of 70 and 69.
Three spots in the Open Championship are up for grabs this week to players not otherwise eligible who finish inside the top 10. Riu and Siem are both currently in line to punch tickets to Royal Liverpool, while Ulsterman Michael Hoey is in position to grab the third spot after carding a 5-under 66, one of the low rounds of the day.