Tony Finau ended a high-scoring first day with the outright lead as Rory McIlroy and Tiger Woods both made encouraging starts to The Memorial Tournament.
With Muirfield Village playing substantially tougher than the relatively friendly set-up for last week's Workday Charity Open on the same course, only 24 of one of the strongest fields in PGA Tour history managed to break par in the opening round.
But Finau showed contempt for the difficult conditions and carded nine birdies in a six-under 66 which earned him a one-stroke advantage over Ryan Palmer, with US Open champion Gary Woodland one further back alongside Brendan Steele.
McIlroy overcame a few errant tee shots to carve out a hard-working 70, with Woods started and finished with birdies as he returned a laudable 71 in his first competitive outing since hosting the Genesis Invitational five months ago.
But the star-studded field are looking upwards at Finau, who was level par after eight holes before making three straight birdies around the turn and adding two more at 14 and 15, although he did drop his third shot of the day when he blazed his tee shot to the short 16th way right of the target.
However, he responded with back-to-back birdie to close out the low round of the day, and he admitted he rode his luck at times, particularly when he got a favourable bounce after a misdirected shot at the 11th.
"I think I scored it about as good as I could," he said. "I got some good breaks early on my back nine, mainly No 11 when I hit it left of the hazard and was able to get a clear lay-up there. I hit a second shot that landed on a sprinkler head and it jumped up next to the green and was able to make a birdie-four there.
"I think on a golf course like this in these conditions, it really forces you to think about every shot and stay in the present. Fast greens, tough pin locations, and then the wind - you've got to deal with the wind. Whenever you're thinking about wind on a putt, you know it's pretty tough.
Palmer managed to keep a bogey off his card and managed five birdies, including three in a row late in his round which lifted him into outright second ahead of Steele and Woodland who played 17 holes without a blemish only to stumble to his lone bogey of the day at the last, where he pushed his drive into the right rough and could not reach the green in two.
Jon Rahm, one of four players who could dethrone McIlroy as world No 1 this week, made a positive start with a three-under 69, with McIlroy among a large group of 10 players to on two under, a list which also features Jordan Spieth and defending champion Patrick Cantlay.
McIlroy admitted pre-tournament that he had struggled to stay focused without spectators in attendance, and that looked the case again early in his round as he found fairways hard to locate while dropping a shot when he bunkered his tee shot to the short fourth.
But he lifted his spirits with back-to-back birdies at six and seven only for another wayward drive to cost him another bogey at the ninth, and he had to scramble hard to save pars at 11 and 12 before holing from outside 20 feet for birdie at 13, and a sublime pitch to three feet at 15 from an awkward position in the rough set up his fourth birdie of the round.
The world No 1 parred safely in to ensure bragging rights over playing partners Woods and Brooks Koepka (70), with Woods unable to capitalise on a brilliant start which saw him birdie two of the first three holes.
The five-time champion gave both shots back at the sixth and eighth, and he offset a birdie at 15 with a bogey at 16 before finishing with a flourish, a solid iron to 15 feet at the last which he converted for birdie to end the day in red numbers.
Man of the moment Bryson DeChambeau opened with a disappointing 73, although he did thrill the viewers with some remarkable hitting which included drives measuring 407 yards (17th) and 423 yards at the first, where he reduced a tough 473-yard par-four to a drive and a flick with a wedge.
Former champion Justin Rose was two under with five to play, but he had a double-bogey and two bogeys down the stretch and slipped to one over along with reigning Open champion Shane Lowry, while Dustin Johnson four-putted the first to set the tone for an 80, and Rickie Fowler (+9) will also need something big on Friday just to make the weekend.