The Open 2015: Dustin Johnson leads way at St Andrews

Johnson fired a seven-under 65 at St Andrews

Dustin Johnson on the opening day (GETTY IMAGES)

Big-hitting American Dustin Johnson insists he is over his last major heartbreak but, despite taking the first-round lead at the Open, having Jordan Spieth in close pursuit will give him a constant reminder.

Johnson fired a seven-under 65 at St Andrews for a one-stroke advantage over the field but his Chambers Bay tormentor is only two shots back as he chases a historic single-season grand slam.

Somewhat mischievously paired together by the R&A following their final-round tussle in the US Open, which saw Johnson three-putt the last green to hand Spieth his second major of the year, they matched each other virtually shot-for-shot over the first 12 holes.

They were tied at six under until Spieth, who is also the Masters champion, was the first to blink with a bogey at the 13th.

Johnson extended the gap to two with a birdie at the only par five on the back nine, the 14th, and produced important saves at the 16th and 17th.

His advantage over Spieth was stretched to three when his compatriot went into the Road hole bunker and subsequently missed a five-footer for par.

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However, there was one last sting in the tail at the last - although not as painful as last month's 72nd-hole drama - when Spieth sank a curling 20ft birdie and Johnson saw his effort from a similar position roll across the face of the hole.

Such were the scoring conditions for the morning starters there were a host of players in the clubhouse at six under - another Chambers Bay combatant Jason Day, Robert Streb, Retief Goosen and 1999 Open champion Paul Lawrie - with amateur Jordan Niebrugge, Kevin Na, 2010 champion Louis Oosthuizen and 2011 Masters winner Charl Schwartzel a further shot back with Spieth.

But the main focus was the enthralling contest between Johnson, who carded the day's only eagle with a brilliant approach to the 570-yard fifth, and Spieth.

Johnson said on Monday he had no hang-ups about his Chambers Bay near-miss and his opening round at the home of golf suggested as much.

PA