Brooks Koepka and fellow American Bryson DeChambeau are tied for first place after an engrossing opening round at The Masters at Augusta National Golf Club.
Both players ended day one on six under par after shooting rounds of 66.
Three-time major winner Koepka went bogey-free, while DeChambeau tapped-in for birdie at the 18th to draw level having hit the pin with his approach.
Another American Phil Mickelson, who is aiming to become the oldest winner of a Major in history at the age of 48, sits in third on five under as he goes in search of a fourth Green Jacket.
England’s Ian Poulter is joint-fourth alongside world number two Dustin Johnson of the United States on four under.
Koepka, who was unable to compete at the 2018 Masters due to a wrist injury, has won three of the past seven Majors.
Last year, he retained the US Open title before winning the Professional Golfers' Association Championship ahead of Tiger Woods, who finished on two under today.
After managing just one birdie on the front nine, at the second hole, he made five in six from the 10th before parring the last three.
"I'm super-aggressive at a normal event and that kind of backfires sometimes," Koepka told BBC Sport.
"In a normal event that three-putt for par on eight really would have driven me nuts.
"I would have been sitting there for probably five minutes trying to figure out what I did wrong, but I just let things go a lot more easily in a Major."
DeChambeau also produced a strong back nine with birdies at the par-three 12th and par-five 13th prior to becoming the first player since 2013 to pick up a shot on each of the last four holes.
He had earlier posted birdies at the second, fourth and eighth, while his only bogeys of the round came at the third, ninth and 14th.
"I hit my shots beautifully," DeChambeau, the world number six told BBC Sport.
"We changed every shaft on the clubs leading into this.
"It's pretty cool to understand the dynamics around this and there is something special to come."
Spain's Jon Rahm and Australia's Adam Scott, the 2013 champion, are in a group on three under.
They are joined by South Africa's Justin Harding, Thailand's Kiradech Aphibarnrat and the US's Kevin Kisner.
Northern Ireland's Rory McIlroy begun his quest to join an elite group of five players to win each of the Majors on at least one occasion with a one-over 73, while world number one Justin Rose of England finished a further two shots back.
Rose was four over after nine but holed birdies on the 15th and 17th, either side of a bogey at the 16th, as he came home in 75.
Four-time champion Woods led momentarily on three under before a bogey on the 17th dropped him back.
Action at Augusta is due to continue tomorrow.