Ironically, tournament debutant McDowell lies best placed of the Irish players, tied for 54th after shooting a four-over-par 74.

Meanwhile, an ailing Lee Westwood and a fuming Ian Poulter had vastly different tales to tell.

Westwood, suffering from a chest complaint and kept awake most of the night, somehow produced a two-under-par 68 to be in joint third place only one stroke behind American pacesetters Rocco Mediate and Olin Browne.

Poulter, on the other hand, was raging over incidents on the 18th and first greens as he slumped to a seven-over 77.

Having started on the back nine the Ryder Cup star was already five over when his tiny par putt on the 18th almost came out again after going into the cup and hitting the back rim.

On the very next green, amazingly, his two-foot par putt did come back out - and before tapping in for bogey he stood and protested to the rules official following the game.

Poulter called for the tournament director, who arrived on the next hole and told him that while it was unfortunate the situation had been checked and the cups were considered fine.

“That was because I had rammed the flag back in on the first because I didn’t want it to happen to anybody else,” commented the Milton Keynes golfer.

“It has never happened to me before and I have only ever seen it once on a putting green, not in a tournament.

“I was shocked. I hit two perfect putts and you don’t expect to see that. We are in a major golf tournament and I feel it’s a shame. The metal rim is supposed to be an inch minimum below the surface and I was having a tough enough time without that.

“I could shoot three three-unders now and lose by a shot. If I do I am not going to be very happy. And I am choosing my words very carefully here.

“Inside I am raging and I think it’s best to get it out of my system now. The crowd went ‘ooh’ on the 18th and then it happens again and the ball does come out.”

Westwood was considering seeking a doctor after his round. He had started feeling ill last weekend in Maryland, but became much worse on the eve of the event.

“I thought it was sunstroke, but I now think it’s going from the heat into air conditioning,” he said.

“I didn’t feel too great when I got up and for this event you want to be fully fit, but I played great. Any time you shoot two under at a US Open you have got to be pleased.”

Level par with six to play, he birdied the 378-yard 13th and then rolled in a 60-foot putt on the next.

The 16th is probably the hardest hole on the course – it plays as a par five for members – but he made a 30-footer there.

As Westwood went off in search of treatment he was alongside Retief Goosen and Phil Mickelson, first and second last year, and Australian Adam Scott, while Brandt Jobe had joined Mediate and Browne out in front by going to the turn in 32. Mickelson and Scott both had six to play.

Browne, 46 and ranked 300th in the world, nearly pulled out of the event a week ago after a poor first qualifying round. But he decided to stay and scored 59 to make it to Pinehurst.

Mediate is himself 42 and ranked 251st, while there was almost a third unexpected name at the top overnight.

Jobe, yet to win in 191 starts on the US Tour going back to 1987, led on his own when he birdied the long 10th to reach four under, but bogeys at the 16th and 17th brought him back alongside Westwood and Goosen.

Also in the hunt are Luke Donald and Mickelson after 69s and Masters champion Tiger Woods and world number two Vijay Singh, both round in 70. Ernie Els is one behind them and Colin Montgomerie would have been but for a closing bogey.

Paul Casey’s recent troubles continued with a nightmare 15-over-par 85 that left him last of the 156 players. He is now 46 over par for his last seven rounds.

Donald, beaten by Woods by seven shots the last time they played together in a major, underlined the massive strides he has made in two years.

Woods was wayward from the start, but was still able to pick up where he left off at Augusta in April – with a birdie.

His opening drive missed the fairway on the right for the first of several times, but also missed the tangly rough and finished on a sandy path.

Just off the green in two at the 607-yard hole he then chipped to 12 feet and made the putt.

But coming up short of the green on the short 15th and finding the rough at the next did lead to bogeys before he came back with a fine bunker shot to within three feet of the flag at the 565-yard fourth.

Donald, who had to back off from a putt as early as the 12th because of clicking cameras aimed at Woods, almost holed his pitch to the 13th, but then stuttered as well.

He found the left rough at the 16th before chipping over the green and then three-putted the next for another bogey. Unflappable by nature, though, he birdied the first and fourth and came back from another dropped shot at the fifth with another birdie on the eighth.

Donald said afterwards: “I was a little bit heavy-handed on 16 and 17 – they were clumsy bogeys – but overall I am very happy with that.”

Us Open first-timers Jonathan Lomas, Nick Dougherty both shot 72, while Yorkshire’s Simon Dyson and Scot Stephen Gallacher, two more first-timers, struggled. Dyson returned a 79 and Gallacher was on the same mark.

Just nine players ended up breaking par and Donald and Mickelson were in a tie for sixth with former winner Steve Jones and South Korean KJ Choi.

Mediate eagled the long 10th by pitching in and Choi sank a 30-foot putt for eagle after driving the green on the 336-yard third.

Collated scores after the first round of the United States Open championship, Pinehurst no 2, Pinehurst, North Carolina (USA unless stated, par 70, x denotes amateur):

67 Olin Browne, Rocco Mediate

68 Retief Goosen (Rsa), Lee Westwood (Gbr), Brandt Jobe

69 Steve Jones, Luke Donald (Gbr), KJ Choi (Kor), Phil Mickelson

70 David Toms, Tiger Woods, Tommy Armour, Adam Scott (Aus), Vijay Singh (Fij), Toru Taniguchi (Jpn), Bob Estes

71 Ernie Els (Rsa), Shigeki Maruyama (Jpn), Chris DiMarco, Bob Tway, Peter Lonard (Aus), John Cook, Jason Gore, Mark Hensby (Aus), Angel Cabrera (Arg), Stephen Ames (Can), Thomas Bjorn (Den), Jim Furyk, Sergio Garcia (Spa), Fred Couples, Michael Campbell (Nzl)

72 Jonathan Lomas (Gbr), Rory Sabbatini (Rsa), Nick Price (Zim), Nick Dougherty (Gbr), Jeff Maggert, Peter Jacobsen, Stephen Allan (Aus), Paul Claxton, Richard Green (Aus), Robert Allenby (Aus), Colin Montgomerie (Gbr), Steve Flesch, Nick O’Hern (Aus), Geoff Ogilvy (Aus)

73 Corey Pavin, JJ Henry, Michael Allen, Josh McCumber, Spencer Levin, Fred Funk, Stewart Cink, Ted Purdy

74 Bill Glasson, Yong Eun-yang (Kor), Tom Pernice, Bernhard Langer (Ger), Graeme McDowell (Irl), DJ Brigman, John Mallinger, Rob Rashell, Keiichiro Fukabori (Jpn), Franklin Langham, Carlos Franco (Par), Shingo Katayama (Jpn), John Daly, Tim Herron, Lee Janzen, Zach Johnson, Steve Elkington (Aus), David Howell (Gbr), Soren Kjeldsen (Den), Aaron Barber, David Oh

75 Thomas Levet (Fra), John Rollins, (x) Ryan Moore, Todd Hamilton, Kenny Perry, (x) Matthew Every, Matt Kuchar, Eric Meichtry, Kyle Willmann, Omar Uresti, Frank Lickliter, Robert Karlsson (Swe), Mike Weir (Can), (x) Trip Kuehne, JL Lewis, Casey Wittenberg, Ian Leggatt (Can), Jose-Filipe Lima (Por), Derek Brown

76 Len Mattiace, Justin Leonard, David Duval, Scott Verplank, Jerry Kelly, James Driscoll, Arron Oberholser, (x) Michael Putnam, Lee Rinker, Scott Parel, Tim Clark (Rsa), Scott McCarron, Peter Hanson (Swe), Chris Nallen, Paul McGinley (Irl), Ben Curtis, Euan Walters (Aus), Craig Barlow, Nick Gilliam

77 Craig Parry (Aus), Chad Campbell, Ian Poulter (Gbr), Steve Conran (Aus), (x) David Denham, Robert Gamez, Carl Pettersson (Swe), Tom Lehman, Peter Hedblom (Swe), Charles Howell, Davis Love, Padraig Harrington (Irl), Ryuji Imada (Jpn), JP Hayes, John Merrick, Scott Gibson, David Hearn, Clint Jensen

78 Steve Lowery, Rich Beem, Shaun Micheel, Jerry Smith

79 Brandt Snedeker, (x) Lee Williams, Simon Dyson (Gbr), Patrick Damron, Joe Ogilvie, Miguel Angel Jimenez (Spa), Bart Bryant, Stephen Gallacher, Sal Spallone, Michael Ruiz

80 Rod Pampling (Aus), Conrad Ray, Nick Jones

81 Stuart Appleby (Aus), Eric Axley

82 (x) Luke List, Jay Haas, James Benepe, Wil Collins

83 Troy Kelly, (x) Pierre-Henri Soero (New Cal)

85 Paul Casey (Gbr)