Rory McIlroy said he was 'really pleased' with his three-under-par 68 first round at the US Open.
American Scott Piercy set the early pace at Pebble Beach finishing on -4.
Playing in the second group out at 6:56am local time, Piercy birdied the second, fourth and fifth to reach three under par and enjoy a two-shot lead over a four-strong group which included Spain's Jon Rahm.
Rahm had started his round on the back nine and made the first birdie of the day on the difficult par-four 10th, but playing partners McIlroy and Marc Leishman both made bogey.
McIlroy found the right-hand side of the fairway off the tee but pulled his approach into a greenside bunker and was unable to get up and down.
The first seven holes at Pebble Beach offer the best chance to pick up shots and Piercy was taking full advantage, a brilliant approach to the par-five sixth leaving him a tap-in eagle.
Rahm, who had holed from 35ft on the 10th, maintained his flying start with further birdies from close range on the 11th and 12th, while McIlroy came agonisingly close to a birdie on 11 and parred the next to remain one over.
Piercy's brilliant start came to a halt on the eighth after he tangled with thick rough off the tee, the resulting double bogey dropping him into a tie for the lead with Rahm.
England's Tyrrell Hatton, Denmark's Thorbjorn Olesen and South African Louis Oosthuizen were part of the group a shot off the pace, Oosthuizen having holed out from 96 yards for an eagle on the 11th.
McIlroy was three strokes behind playing partner Rahm after a birdie on the 13th got him back to level par.
Piercy regained the outright lead with a birdie on the 12th but the ideal conditions meant there were plenty of contenders in close pursuit.
Rahm recovered from his first bogey of the day on the 17th with a two-putt birdie on the par-five 18th, while Oosthuizen, Rickie Fowler and Gary Woodland were also three under.
McIlroy moved into red figures with a birdie on the 17th but had to settle for a par on the 18th after finding rough off the tee and a fairway bunker with his second.
McIlroy picked up further shots on the second and third and holed from 15 feet for par on the fifth after duffing his chip from heavy rough just off the green.
"I'm really pleased, it's tough starting on that 10th in the morning," McIlroy told Sky Sports. "I came back well and didn't make a bogey.
"I played the last 17 holes in four under par. It's benign conditions, very soft for a US Open, so you needed to get out there and shoot something in the 60s.
"I'm happy with my day's work. There are a few tee shots out there that it's easy to hit it into the Pacific Ocean. I putted well, that's something I'm going to have to do this week."
Former champion Graeme McDowell, who won at Pebble Beach in 2010, was two under par following birdies at the fourth and sixth.