Phil Mickelson leads The Open by three strokes but will have mixed emotions after missing out on becoming the first man to shoot 62 in a major.

Mickelson, who won the Claret Jug in 2013, was in fine form during his first round at Royal Troon, combining accuracy off the tee with an excellent short game. That formula took him to eight under par as he approached the last and a chance to take sole possession of the lowest round in major history. 

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Despite atoning for a somewhat wayward tee shot with an approach that left him 16 feet for an historic birdie, Mickelson's excellent putt somehow lipped out.

Mickelson heads a leaderboard dominated by Americans, with Patrick Reed and Germany's Martin Kaymer three shots off the lead in a tie for second place on five under par. Reed had served as the clubhouse leader prior to Mickelson's record-tying 63, carding a score of 66 that was matched by Kaymer, with the two-time major champion recording a bogey-free round.

Zach Johnson is firmly in contention for back-to-back titles at four under par, but things would have been even better for the defending champion if not for a poor finish.

Johnson's first bogey of the round came at 17 as he failed to convert a difficult up-and-down following a disappointing tee shot. And Johnson duly dropped another shot at the last to leave him in tied fourth, level with compatriots Justin Thomas, Steve Stricker, Billy Horschel and Tony Finau.

Andy Sullivan and Soren Kjeldsen also finished their rounds on 67, with Keegan Bradley joining the crowded group on four under par in his pursuit of a second major title.

However, U.S. Open champion Dustin Johnson finds himself eight shots off the pace after he could only manage a level-par 71.

There was huge disappointment for England's Chris Wood, who was forced to withdraw from the tournament due to a re-occurrence of a neck injury.