Sizzling Stadler in charge at French Open
Kevin Stadler of the United States watches his tee shot on the sixth hole during the first round of the Travelers Championship golf tournament at the TPC River Highlands on June 19, 2014 in Cromwell, Connecticut - by Jim Rogash
Former champion Marcel Siem of Germany was second after his round of 65, while Scotland's Stephen Gallacher is a further shot back as blue skies and warm temperatures produced perfect conditions on the opening day of the oldest continental European tournament.
Defending champion Graeme McDowell of Northern Ireland had a patchy round as he came home in one under par while US Open champion Martin Kaymer clawed back three birdies on the back nine to stay in touch on one over.
Stadler, who was part of the first father-son lineup to play at the Masters earlier this year when he competed alongside dad, Craig 'the Walrus' Stadler, began to hit form as early as the second hole par-three when he sunk a 15-footer for birdie.
Another good putt at number three to move two under and further birdies at six, ten, 11, 12 and 14 set up the day's outstanding round for the 34-year-old, who did not record a bogey.
"That was one of my best rounds of the year for sure. Not making bogey was something I didn't think possible in my practice rounds," said a delighted Stadler.
"It's one of my favourite courses and it's spectacular. It was a great day and I'm happy to be over here, just came for a bit of fun but I definitely enjoyed the golf course from the get-go. It's a wonderful place and I had a very good day." he added.
-- Challengers close behind --
Siem, winner of the 2012 French Open, again found the challenging Albatross layout to his liking as he nailed eight birdies, including three of the last four holes to initially sit alone at the top of the leaderboard before Stadler's late charge.
"I think if I can keep my concentration level, I'm going to get some good results in the next two weeks hopefully," said Siem, who recently became a father.
"I was really tired and had a late tee-time yesterday in the Pro-Am, an early one this morning and I can't wait to go to bed, I need to get my batteries loaded up."
Gallacher had a chance to join Siem in second when he bogeyed the final hole to slip to a 66 after seven birdies put him in prime position.
The 39-year-old, who is the nephew of former Ryder Cup captain Bernard, got off to a scorching start with four birdies on the front nine after starting his round at hole number ten.
"I had an eight-foot putt to go eight under but that's what this course can do," said Gallacher who faces five tournaments over the next six weeks in a bid to crack into the Ryder Cup team.
"I've struggled a bit the past few weeks but I've been working hard and I pretty much hit all of my targets today," added the player who hails from Linlithgow, just a few miles from Gleneagles where the Ryder Cup will by played in September.
The top Frenchman was Victor Riu, who was four shots back on 68, but compatriot Victor Dubuisson struggled with hay fever and had a day to forget as a costly triple bogey on the opening hole left him at the wrong end of the leaderboard on five over and struggling to make the cut.