Dustin Johnson sounded an ominous warning to grand slam-chasing Jordan Spieth by outmuscling the youngster to power his way to the top of the leaderboard in the British Open first round.
The 31-year-old Johnson gave an object lesson in big hitting as he bulldozed his way to a pacesetting seven-under-par 65 in becalmed early weather conditions at the iconic Fife links.
Sharing second place on 66 are fellow Americans Zach Johnson and Robert Streb, South African Retief Goosen, 1999 champion Paul Lawrie of Scotland, England's Danny Willett and Jason Day of Australia.
Spieth, bidding to add golf's oldest major to his wins at this year's US Masters and US Open, tucked in two strokes behind countryman and playing partner Dustin Johnson but is all too well aware of the size of the task that could lie ahead.
While Johnson and Spieth were showing off their dazzling skills, former world number one and twice St Andrews champion Tiger Woods looked a pale imitation of his old self as he slumped to a sad four-over 76.
The 14-times major winner made a wretched start when he dunked his approach into the Swilcan Burn on the first hole and that set the tone for a litany of errant strokes.
"The guys have been shooting good numbers, unfortunately I did not do that," said Woods after ending the day tied 139th in a field of 156.
"Hopefully the conditions will be tough tomorrow and I can put together a good round and move up the board."