England's Matt Fitzpatrick and American Max Homa spoke about the unforgiving nature of The Country Club at Brookline, despite being two of 25 players to finish Thursday's opening round under par.
Fitzpatrick, who shot a two-under 68, is tied for seventh place, with a bogey-free front nine that featured birdies on the fifth, eighth and ninth holes, before three bogeys and two birdies on his second nine.
On a course billed as favourable to the long-drivers, Fitzpatrick did not finish inside the top-50 four driving distance on Thursday, but made up for it with terrific precision.
He was top-10 in driving accuracy, hitting 10-of-14 fairways, top-10 in strokes gained off the tee (1.26) and fifth in strokes gained around the green (2.59).
Speaking to the media after his round, he said enjoys the challenge the course presents, having also won the 2013 U.S. Amateur Championship there.
"I've got great memories of the place, and the whole time I've been out, I see shots that I hit and I see the places I was," he said. "I think because of that I'm a bit more at ease.
"I think the tight fairways… are a big deal. There is just a premium on driving accuracy. From there – I think you have to putt your way around here… you have to think about it.
"[Compared to the 2020 U.S. Open at Winged Foot] I feel like there is a lot of drivers, but you are then going into the greens. You can't miss on the left side because the slope is so severe, and you have no shot.
"You might decide to play to a corner on 18 with a three-wood, or you just take it even further with driver. I just think it gives you plenty of options and things to think about around this place."
Homa, who finished one shot further back than Fitzpatrick at one under, said he enjoyed his day, but was blown away by the difficulty of the greens.
"It was good – the weather was really nice in the beginning of the day," he said. "The wind picked up, and it got a little more tricky than difficult.
"But the greens are just so – they're crazy, so it's just really hard to leave yourself good looks for birdie. I missed a bunch of putts today, but they just never felt very easy."
He added: "I have to get my speed better on the greens. They're very uncomfortable.
"I don't know how to make myself comfortable, but just maybe try to find a speed that I like seeing the ball go in at a little more, because right now my pace just feels a little bit inconsistent."
Set to start Friday's second round on the back-nine, Homa said he expects that to be the far tougher starting position due to the difficulty of holes 10 and 12 right out of the gate, but he acknowledged "it's the U.S. Open – it's always going to be hard."