Viktor Hovland fired a seven-under-par 64 to take a one-shot clubhouse lead Thursday as play was suspended at the PGA Tour's RBC Heritage tournament in South Carolina.
Hovland, fresh from a seventh place finish at the Masters, finished with back-to-back birdies to complete a bogey-free first round at Harbour Town Links on Hilton Head Island.
That left him alone atop the leaderboard, one clear of Brian Harman on six under. Jimmy Walker and England's Aaron Rai were out on the course also on six under when play was suspended due to darkness.
Teeing off on the back nine, Hovland started slowly with four straight pars before building momentum near the turn with three birdies in four holes, including a 16-foot birdie putt on the 17th, his eighth hole.
He rolled in another long birdie putt from 18 feet on his 12th hole and then added three more birdies down the stretch to head the leaderboard.
"That was really good," Hovland said afterwards. "Hit some really nice shots starting the day but didn't make the putts. It was a little frustrating, but stayed patient and just kept on hitting great shots.
"Then the putter started heating up, and it felt very stress-free from there on in."
A group of six players completed their rounds on five under while four others, including Xander Schauffele and Rickie Fowler, are a further shot back on four under, three off the lead.
But newly crowned Masters champion Jon Rahm had a day to forget after firing a one-over-par 72.
Although the Spanish world No 1 started solidly, picking up an early birdie on the fourth, his round unravelled with three straight bogeys on the sixth, seventh and eighth holes that left him two over at the turn.
He clawed back two shots with back-to-back birdies on the 13th and 14th holes, but then dropped back to one over with his fourth bogey of the day on 16.
"It was what it was," Rahm said of his round. "It wasn't anything – nothing was particularly good. Nothing was particularly awful. I would have been happy pretty much with anything under par, but it just wasn't to be."
Rahm admitted he was still struggling with fatigue after his emotional Masters win on Sunday.
"I hate to make excuses, but a couple of the swings towards the end were my body being tired," Rahm said.
"I think for the most part I did a pretty good job. It could have been a lot worse, been very ugly. We've got it started. Just three days to make it back."