Rickie Fowler held a share of the clubhouse lead midway through the opening round of the Aberdeen Standard Investments Scottish Open at Gullane.
The American, who won this event in 2015 the last time it was staged over this course, carded five birdies, a single bogey and an eagle in his opening round to join Robert Rock on six under.
After a hat-trick of gains from the second, Fowler drove the par four sixth and holed his putt for eagle as he raced to the turn in 30.
In near-perfect conditions, Fowler looked to be on course to threaten the course record of 63 when he birdied the 11th and 12th.
However, he tangled with a bunker on the 13th to drop his only shot of the day.
"I love playing links golf and being able to use your imagination and hit different shots," said Fowler.
"I feel like this golf course, you go around and you hit pretty much every club in your bag. You hit driver quite a bit.
"It's just fun. Especially once the wind starts to blow a bit."
Rock made six unanswered birdies, while out on the course Spain's Scott Fernandez and Swede Jens Dantorp were also six under approaching the closing holes.
The quartet were a shot clear of England's Matthew Southgate, South African Richard Sterne, Scotland's Peter Whiteford and France's Julien Guerrier - who playing alongside Rock had also been six under before a bogey at the last.