The US Open golf tournament has got off to a flying start, with two players hitting hole-in-ones in the opening round and one of them just missing out on a second.

The Winged Foot course is normally a brutal test for golfers — when Australia's Geoff Ogilvy won the US Open title here in 2006, his winning total was 5-over par. Many people feel this week's champion will struggle to get near par for the 72 holes.

But on a benign opening day at the course in Mamaroneck, New York, the world's best golfers took the layout apart — and not one but two of them managed aces at the par-three seventh.

First up, American Patrick Reed stepped up at the 151-metre hole and hit a perfect nine-iron tee-shot that took one hop and landed straight in the cup.

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There were a few smiles and some polite reaction from his playing partners, but with fans not allowed at this week's second golf major of 2020 due to the COVID-19 pandemic, there was none of the normal excitement seen after an ace.

"It would have been nuts. Up here in New York, the fans are amazing," he said.

Reed — who two holes earlier had taken a nasty six on the par-four fifth — ended the day in a tie for second at 4-under, one shot behind fellow American Justin Thomas.

A few hours later, next up was 24-year-old Will Zalatoris, who took the same club but a different approach. His nine-iron bounced a handful of times on the green before rolling into the hole.

Not content with one, Zalatoris nearly had another on the 13th, when his tee-shot bounced off the flagstick to narrowly avoid going in.

Thomas went into the week saying it was a "different kind of fun" to grind out pars, to hit middle irons to difficult pins instead of the low scoring at so many other tournaments.

He delivered six birdies and finished with a 25-footer on the 18th on a putt he barely moved to get it started down one of the many wicked slopes on Winged Foot's greens.

He leads from a group of three — Reed, Belgium's Thomas Pieters and American Matthew Wolff.

One shot further back are Rory McIlroy, Lee Westwood and Louis Oosthuizen.

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"Yeah, 65 is fun no matter where you play, especially at Winged Foot," Thomas said.

"I was in a really good frame of mind, and I was focused. I just was sticking to my routine and playing every shot, as opposed to getting ahead of myself.

"It's one of those rounds where … next thing you know, you make the putt on 18, you're done for the day."

He played with Masters champion Tiger Woods and PGA champion Collin Morikawa, who could not get done fast enough.

Woods was in five bunkers through five holes and then appeared to steady himself with three straight birdies around the turn to get under par, but only briefly. He made three bogeys coming in, still had a chance to post a reasonable score and then let it get away.

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From short of the steep shelf fronting the 18th green, he flubbed a flop shot, pitched the next one about 2.4 metres beyond the pin and missed the putt to take double bogey for a 73.

"I did not finish off the round like I needed to," Woods said, a feeling he conveyed five more times out of the six questions he faced after his round.

Neither did Morikawa, who shot 40 on the back nine for a 76.

Zach Johnson had an even-par round to start — like many his card was full of birdies and bogeys.

His highlight came on the first hole, where he ran his putt from the edge of the green four metres past the hole, using the contours of the green to feed it back down the slope and in for a brilliant birdie.

Tough day for the Australians

There were nine Australians in the field for the US Open — and despite the helpful conditions, none of them managed to shoot par or above.

Adam Scott hit four birdies and five bogeys in a 1-over par 71, the same score as Cameron Smith.

Jason Day (2-over) had a tough start, with a double bogey on the par-three third.

As Day put it, he "half-scrapped" the ball out to his right on his second shot and ended up on the downslope of a bunker.

"It was just outside, and then [I] kind of just went straight underneath it, left myself in the rough again over the bunker," Day said.

"It was a tough lie, going back into the grain … and I hit it, and it came out left, went down the hill - nearly holed the fourth [shot], but that's the way it is."

Lucas Herbert also shot a 72, while Marc Leishman was a further shot back on 3-over.

Scott Hend was 4-over after the opening round, Curtis Luck was 5-over, Matt Jones shot a 76 and Melbourne amateur Lukas Michel had a 10-over par round of 80.

ABC/AP