Clarke - opened with a 65 to lead (Getty Images).

Darren Clarke began the United States PGA Championship with a dazzling 65 at a Whistling Straits course which on Monday he reckoned was so "brutally tough" it should have a par of 77.

On the lunar landscape beside Lake Michigan the Ulsterman incredibly birdied six of the first eight holes and nine of the first 14 and his seven-under-par score - his best-ever start to a major - put him one ahead of Ernie Els and Justin Leonard.

England's Luke Donald, pushing hard for a Ryder Cup debut, had eight birdies himself in a 67, one better than Padraig Harrington, but Tiger Woods' two-year wait for another major looks certain to go to three years after he slumped to a 75, the same as Lee Westwood.

Phil Mickelson - first, second and third in the first three majors of the season - is tucked in nicely on three under alongside Paul McGinley and as for Ian Poulter, he matched the 73 of Colin Montgomerie and Justin Rose, but created another fashion sensation when he followed up his Union Jack trousers of the Open last month with the colours of the American flag this time.

Right leg red and white stripes, left leg blue with white stars.

On that Clarke, who at the Masters in April unveiled pink and white pinstripe trousers with white turn-ups, commented: "He looks great, but you won't see me in them. There's quality and there's style."

Both words applied to his golf as he forced his way to the top of the leaderboard of a major for the first time since the Masters last year.

He led by three after a first day 66 then, but fell back to 28th and could not hold on to a four-stroke advantage in the 1997 Open at Troon either.

Those experiences have taught him not to look too far forward and two days before his 36th birthday he said: "I am obviously very pleased because on Sunday I did not think I would be shooting 65 on Thursday, but I would definitely expect this course to bear its teeth.

"It was softer after the rain we had, it was not blowing hard and some of the pins were reasonable to get at." Three of the tees were moved forward as well by a total of nearly 150 yards.

"By the end of the week people will be seeing how difficult this course is, but it is a fantastic one as well. And I would still be saying that if I had shot 77."

Having worked with American short-game expert Stan Utley, Clarke had a mere 25 putts compared to the 32 of Woods, whose five-year reign as world number one is now under threat from not only Els, but also Vijay Singh, who shot 67.

Singh has to win and Woods miss the cut, but if Els wins Woods has to come second and if the South African finishes second then he needs to be in the top 16 to hang on to the top spot he has held for a record-equalling 331 weeks.

Clarke birdied the first four holes, but playing partner KJ Choi birdied the first five and with Leonard, the third member of the group, coming home in 31 it was fireworks all the way.

The only man to have two rounds of 60 on the European Tour, Clarke had made only one halfway cut in six visits to the final major of the season, but this lay-out is different to any other and appeared to be inspiring him. He holed-in-one on the 12th in practice.

Donald kicked off with three birdies and when he pitched to three feet at the 14th his tally was up to eight and he was six under.

But the winner of the Scandinavian Masters two weeks ago failed to get up and down from off the green at the 518-yard 15th - a par four despite its length - and slipped two behind.

"I putted atrociously," said Woods, although he was put off by a photographer on the tee of the long 11th - his second - and wound up taking a double-bogey seven there.

He was paired with Singh and John Daly, but Daly kissed goodbye to his Ryder Cup hopes with an 81 containing a quadruple bogey eight on the 18th. there appears no chance of him getting a wild card from Hal Sutton.

Els, who finished a shot behind Mickelson at the Masters in April and lost a play-off to Todd Hamilton in the Open, said: "I made some putts, but I drove it well and that was the key.

"I can't bring back what happened (earlier this season) and although I think about it every now and again it is done, history. I have got another chance here and I am excited about that."

Harrington was as disappointed as Woods when he stood two over after six, but he then had six birdies, including the last three holes, for a 68 to be handily placed.

"I would have taken that when I started - and certainly when I was two over," he said.

Paul Casey managed only a 74, but Brian Davis, desperate to get back in the Ryder Cup reckoning, shot 70 and David Howell and Phillip Price returned 72s.

Graeme McDowell took 75 in his first-ever American major, but it became a 77 when a two-stroke penalty was imposed for his caddie raking a bunker on the 15th while he had still to play a second shot out of it.

Scott Drummond, shock winner of the Volvo PGA title in May and another making his debut in a major in the States, could feel very satisfied with a 71, but not so Ian Woosnam, who slumped to a 79, while Nick Faldo scored 72.

On his trousers Poulter, ninth in the cup race just behind Howell, commented: "Like the Union Jacks they will go to charity - if someone wants to pay enough. I think the other players are half-expecting something a bit wacky this week."

Collated first round scores (USA unless stated, par 72):

65 Darren Clarke (Gbr)

66 Justin Leonard, Ernie Els (Rsa)

67 Vijay Singh (Fij), Scott Verplank, Luke Donald (Gbr), Briny Baird

68 Jay Haas, KJ Choi (Kor), Padraig Harrington (Ire), Loren Roberts, Chris DiMarco, Tim Petrovic, Stuart Appleby (Aus), Stephen Ames (Can), Geoff Ogilvy (Aus)

69 Paul McGinley (Irl), Chris Riley, Carlos Franco (Par), Phil Mickelson, Duffy Waldorf

70 Scott McCarron, Brian Davis (Gbr), Craig Parry (Aus), Pat Sheehan, Charles Howell, Ben Crane, Jose Maria Olazabal (Jpn)

71 Joey Sindelar, Adam Scott (Aus), Matt Gogel, Carl Pettersson (Swe), Brad Faxon, Roy Biancalana, Robert Allenby (Aus), Scott Drummond (Gbr), Bob Tway, John Huston, Michael Campbell (Nzl), Joe Durant

72 Tom Byrum, Skip Kendall, Eduardo Romero (Arg), Robert Gamez, Harrison Frazar, Jeff Sluman, Mark Calcavecchia, David Howell (Gbr), Shigeki Maruyama (Jpn), Phillip Price (Gbr), Brendan Jones (Aus), Chip Sullivan, Jean-Francois Remesy (Fra), SK Ho (Kor), Fredrik Jacobson (Swe), Tommy Armour, David Toms, Todd Hamilton, Nick Faldo (Gbr), Hidemichi Tanaka (Jpn), Zane Zwenke

73 Ted Purdy, Ian Poulter (Gbr), JL Lewis, Sergio Garcia (Spa), Nick O'Hern (Aus), Stewart Cink, Ben Curtis, Steve Flesch, Craig Thomas, Rod Pampling (Aus), Jonathan Byrd, Hale Irwin, Chad Campbell, Justin Rose (Gbr), Mark Brooks, Hal Sutton, Colin Montgomerie (Gbr), Brian Bateman, Mike Weir (Can), Arron Oberholser, Mark O'Meara

74 Bo Van Pelt, Jonathan Kaye, Billy Andrade, Woody Austin, Raphael Jacquelin (Fra), Rocco Mediate, Heath Slocum, Bernhard Langer (Ger), Stephen Leaney (Aus), Paul Casey (Gbr), Niclas Fasth (Swe), Mark Hensby (Aus), Brenden Pappas (Rsa), Angel Cabrera (Arg), Kevin Sutherland, Brett Quigley, Paul Azinger, Peter Lonard (Aus), Thomas Levet (Fra), Shingo Katayama (Jpn), Fred Funk

75 Mike Small, Ricardo Gonzalez (Arg), Tim Clark (Rsa), Alex Cejka (Ger), Joe Ogilvie, Jim Furyk, Trevor Immelman (Rsa), Tiger Woods, Lee Westwood (Gbr), Bob Estes, Alan Schulte, Tom Pernice, Zach Johnson, Steve Schneiter, Sean English

76 Tim Fleming, Ron Philo, Kenny Perry, Scott Hoch, Miguel Angel Jimenez (Spa), Dave Tentis, Frank Bensel, Jerry Kelly, Jesper Parnevik (Swe), Quinn Griffing

77 Graeme McDowell (Gbr), Tim Herron, Robert Thompson, Cary Hungate, Mike Northern, Jeff Coston, Shaun Micheel, David Duval, Jeffrey Lankford, Kirk Triplett, Bill Britton, Bruce smith

78 Bob Sowards, Joakim Haeggman (Swe), Rich Beem

79 Mike Schuchart, Ian Woosnam (Gbr), Davis Love, JR Roth

80 Steve Lowery, Tetsuji Hiratsuka (Jpn), Mark Evenson, Thongchai Jaidee (Tha), Frank Lickliter, Mike Baker

81 Rory Sabbatini (Rsa), John Daly

Retired: Dudley Hart

Withdrew: Greg Norman (Aus)