Dustin Johnson's seven-under-par round of 65 at St Andrews has given him a one-shot lead a quarter of the way through The Open.
The world number four was in a group with Jordan Spieth, the man to whom he gifted the US Open at Chambers Bay last month with a three-putt on the final hole, and finished two shots clear of his compatriot.
Spieth is trying to become the first man to win the first three Majors in a calendar year, but could not match Johnson as the duo benefited from kinder weather conditions earlier on.
Johnson is one shot clear of a group of six - namesake Zach Johnson, 1999 champion Paul Lawrie, South African veteran Retief Goosen, England's Danny Willett, world number nine Jason Day and Robert Streb - who posted 66.
Behind them are five more on five-under, with the last man to win at St Andrews, Louis Oosthuizen, shooting 65 like Spieth.
The top of the leaderboard is dominated by the early starters as those in the afternoon had to deal with stronger winds on the East coast of Scotland.
Rickie Fowler, winner of the Aberdeen Asset Management Scottish Open at Gullane last weekend, is tied-67th after a level-par 72, while England's best hope, Justin Rose, who played with Fowler, went round in 71 to lie six behind Johnson.
Three-time Open champion Tiger Woods, meanwhile, was one of the few players who struggled in the morning.
The world number 241 shot his highest ever first round in an Open by posting a four-over 76.
The 17th 'Road Hole' didn't produce a single birdie on the opening day as players struggled to get near the flag just past the notorious greenside bunker.
