South African Branden Grace, three times a winner this season, equalled the European Tour record with a 12-under-par 60 at Kingsbarns when the Dunhill Links Championship.
Grace had an eagle and 10 birdies - five of them in a row to finish with - to break Lee Westwood's course record by two. Frenchman Victor Dubuisson was two shots off the lead on 62 after breaking the course record at St Andrews.
Damian McGrane and Shane Lowry are the best of the Irish on three under, while Padraig Harrington is two shots further back.
Grace became the 14th player to shoot a 60 on the European Tour.
Northern Ireland's Darren Clarke, the 2011 British Open winner, is the only man to card two 60s on the circuit, in 1992 and 1999.
Long-hitting Frenchman Dubuisson broke the previous St Andrews best of 63 held by world number one Rory McIlroy, former top-ranked player Luke Donald and fellow Briton Simon Dyson.
Young Dane Thorbjorn Olesen was also on form at the famous Old Course, returning a 63 in the $5 million Dunhill pro-am tournament.
Speaking after his round, Branden Grace said: "I never really made anything long," he said. "It was all 12 to 15-footers and it's nice just to have a bogey-free round on a links.
"We were lucky with the weather, but you still have to get it in the right spots and get it around."
His eagle came on the 565-yard 16th, his seventh, and took him to five under, but it was on the outward half where he really went into overdrive.
Grace birdied all but the second and fourth and came to the 558-yard ninth needing an eagle for the 59, but pushed his second wide before pitching to a foot.
Ryder Cup hero Martin Kaymer (70) played at the more testing Carnoustie layout and missed a par putt at the 18th of a similar length to the one he holed in Chicago last Sunday to win the trophy for Europe.
"The putter was not really hot but in general you've got to play solid at the toughest course we play here," the 2010 US PGA champion told reporters.
"It's a very nice feeling to come here after Sunday. A lot of people told me it was their best sporting experience on TV," added the German.
Kaymer's Ryder Cup team mates Paul Lawrie (75) and Peter Hanson (72), both playing at Carnoustie, also found the going tough.
British Open champion Ernie Els returned a 73 at Carnoustie where the best score midway through round one was a 67 by England's Oliver Wilson.