Shinnecock Hills lived up to its reputation as one of the toughest tests in golf on the opening day of a fog-delayed US Open.

When play did get under way, two hours later than scheduled, only six of the early starters broke par as strong winds buffeted an already tricky course on Long Island, New York.

Among them was world number two Rory McIlroy, whose one-under 69 left him one behind unfancied American Sam Stevens as the 78 players in the later wave headed out onto the course

And with the blustery conditions forecast to strengthen as the day wears on, both players will expect to remain firmly in the mix, given that in the four previous US Opens held at this venue, there have been 1,792 rounds and only 161 (9%) have been played under par. In fact, just three players have ended up under par after 72 holes.

Much of that was down to the substandard playing conditions at Shinnecock in both 2004 and 2018 with players accusing championship organisers the United States Golf Association (USGA) of "losing the course".

Speaking recently to the No Laying Up podcast, USGA's John Bodenhamer, the man responsible for course set-up this year accepted the previous conditions had been suboptimal but insisted they had "learned a lot".

For example, water is being hosed onto the greens during the opening two rounds to stop them from drying out, and to keep the grass alive.

The US Open is generally regarded as the toughest of tests though and all the players spoke of needing to remain patient. And that patience was tested from the off on Thursday with low-lying cloud and fog shrouding the course.

However, once it had been dispersed by the strong gusts whipping in off the Atlantic Ocean, the true nature of the challenge ahead was laid bare.

Thick rough, five inches deep, flanks the fairways. Wispy fescue and undulating and fast greens add further layers of complexity to Shinnecock's fearsome reputation.

Not that McIlroy seemed perturbed as the wind gusted beyond 30mph across the 7,440-yard track.

The six-time major winner, who started on the 10th, knocked in two birdies in the opening three holes and even bogeys at the 13th and 16th holes did not appear to provide him with any cause to revaluate his approach.

During the round McIlroy, who successfully defended his Masters title in April, told Sky Sports pundit and Solheim Cup great Mel Reid that because conditions were "consistent"' he was not finding things too bad at all.

He aptly demonstrated that after the turn with a birdie at the third and by carding a sensational eagle on the par-five fifth after hitting his tee shot a wind-assisted 396 yards before nudging his second shot to 11 feet.

Even though he was unable to end strongly, McIlroy has taken great satisfaction from his overall display.

"Anything under or around even par is a good score," said McIlroy who won his solitary US Open title in 2011.

"It was a day to keep yourself in the tournament and not shoot yourself out of it, which is exactly what I did eight years ago here," added the 37-year-old who opened with an 80 in 2018 as he went on to miss the halfway cut.

McIlroy's playing partners Ludvig Aberg and Tommy Fleetwood also enjoyed solid starts.

Swede Aberg also shot a 69 while England's Fleetwood knocked in birdies on the fifth and sixth holes - his 14th and 15th - as he posted a level-par 70.

World number one Scottie Scheffler found greens and birdies hard to come by as his bid to become the seventh player in history to complete the career Grand Slam got under way.

Only Gene Sarazen, Ben Hogan, Gary Player, Jack Nicklaus, Tiger Woods and Rory McIlroy are in that exclusive set of winning all four of the men's majors.

And on this evidence, the American, who has topped the rankings for the previous 161 weeks will need to improve on a scrambling two-over 72 which featured four birdies, four bogeys and a double-bogey.

Twice in three holes he cut a bemused figure as his iron shot found the green only for it to spin away from the hole and cost him chances of making a birdie.

Scheffler was far from the only one to endure moments of incredulity.

His playing partner JJ Spaun hit his ball on to the par-three seventh green but by the time the defending champion reached the putting surface a gust of wind had sent it tumbling backwards into a bunker and into a scramble to save his par.

The notoriously tricky par-three 11th hole did for Keegan Bradley's ball in a similar way and while it did not cost him a shot, it underlined why 2010 winner Graeme McDowell had described Shinnecock Hills as "a torture chamber" in the build-up to his first major appearance in eight years after coming through qualifying,

McDowell birdied the 10th and 11th to surge to the top of the leaderboard but his card was eventually littered with bogeys and he eventually signed for a six-over 76.

American Keith Mitchell looked set to be another falling foul of the unforgiving terrain when he reached the turn in 41.

However, the 34-year-old became the first player in the tournament's history to hit 40 or worse on one nine and break 30 on the other nine in the same round - his second-half 29 seeing him sign for a level-par 70.

Meanwhile, Australian Adam Scott became only the second man to play in 100 consecutive majors - joining the legendary Jack Nicklaus, who played in 146 on the trot. The 2013 Masters champion opened with a 73.

That was the same score as two-time US Open champion Brooks Koepka, who won the last time Shinnecock Hills held this championship.

They were a shot better off than England's Tyrrell Hatton, while Spaun failed to make a single birdie as he posted a seven-over 77.