Phil Mickelson achieved the rare feat of hitting every fairway as he made a strong start to his bid for a fifth win at the AT&T Pebble Beach Pro-Am in California.
Mickelson opened with a six-under 65 on the Monterey Peninsula course, one of three layouts in operation for the star-studded event this week, leaving the left-hander just one off the lead along with his fellow runner-up from last year, Jason Day.
The evergreen 48-year-old had a quiet front nine before enjoying a run of three birdies in four holes after the turn, and he picked up further shots at 16 and 18 to ensure he would end the day just a stroke adrift of early pace-setters Brian Gay and Scott Langley.
Mickelson, who is chasing his 50th career victory, was flawless from the tee as he hit 13 out of 13 fairways - the first time he recorded a 100 per cent success rate in that department on the PGA Tour since 1998, although he was unaware he had managed this before.
"History was made today," he said afterwards. "To the best of my knowledge it's taken me 27 years and a few months to hit all fairways in a single round in a competition. I may have done it before but I don't ever recall doing it.
"I don't think I've ever done that before, certainly in competition, so that was a big milestone for me. I putted very well too, although my speed was off. I ran a number of putts by, but I made a lot of them coming back and made a lot of short ones."
Day carded seven birdies in his 65, while two-time champion Dustin Johnson and 2017 winner Jordan Spieth also took advantage of the favourable scoring conditions on the Monterey Peninsula course as they opened with 66s, while last week's Phoenix Open runner-up Branden Grace returned an impressive five-under 67 at Pebble Beach.
The South African was five under after only six holes with three birdies and a superb eagle at the second, but he did not manage another gain until the 18th as he settled for a share of ninth place with Johnson and Spieth.
Graeme McDowell enjoyed returning to the scene of his 2010 US Open victory as he made seven birdies in a 68, although he finished in disappointing style when he three-putted from 20 feet on the final green to sign off with a bogey-six.
McDowell was joined on four under by Scotland's Martin Laird, whose 68 was one of the best rounds of the first day at Spyglass Hill, while Masters champion Patrick Reed and two-time victor Brandt Snedeker, who made a remarkable birdie on the 18th at Pebble Beach despite pulling his drive into the beach, were among a large group four shots off the lead.
The much-hyped PGA Tour debut for the unorthodox Ho Sung Choi did not go to plan early on as the South Korean slumped to four over after 10 holes at Monterey Peninsula, but he produced a commendable fightback with birdies at 11, 15 and 16 hauling him back to one-over par.