From Brian Keogh in Tulsa

Darren Clarke's confidence dipped to a new low as temperatures soared at the US PGA in Tulsa.

The struggling Ulsterman, 38, crashed to a seven over par 77 with three double bogeys on his card at Southern Hills.

Cooling early breezes did nothing to help the Dungannon man as he opened with a double bogey six.

And as the thermometer zoomed towards 100F, Clarke did well not to blow his top as he double bogeyed his ninth and 18th holes.

Flushed after his efforts, Clarke held his hands up and said: " I played poorly lads, I just played poorly.

"I had a double at the first and a couple of doubles at the end. I am trying my balls off and I am not getting anywhere."

Needing two pars for a respectable 74, he bogeyed the eighth and then double bogeyed the ninth to finish 10 shots behind surprise clubhouse leader John Daly.

At the 374-yard ninth, he drove to within 61 yards of the green but fluffed his approach into a bunker and took two to get out.

Scratching his head over his finish, Clarke said: "That's just typical of the way it is at the minute. I am not going to moan about it. I am just not hitting good enough golf shots at the minute.

"And for some reason I am compounding every mistake with another one and that double at the last typifies what I am doing at the minute.

"I can only battle on and keep on doing what I am doing. My good stuff is just not good enough at the moment. I am trying my best but it is just not happening."

But Clarke wasn't the only big name to struggle as big John Daly produced his lowest round in a major for 10 years to grab the clubhouse lead with a three under par 67.

World No 1 Tiger Woods slipped from three under after six holes to a one over par 71 with five bogeys and just one birdie in his last 11 holes.

Starting on the 10th, things looked bad for Clarke when he blocked his his eight iron approach 20 yards right and plugged in the bunker.

Caddie Billy Foster said: "There has been a trend where he has been three over after four holes and he just needed a decent start and he got off to the worst possible start."

A birdie at the 458 yard 12th, where he hit a nine-iron to five feet, got Clarke back to one over for the round.

But he failed to take advantage of a string of chances on the way to the turn and then paid the price with a double bogey six at the tough 18th.

After hooking his tee shot into the rough, Clarke chopped the ball forward and then pulled his third shot down the hill and failed to get up and down.

Out in three over par 38, he parred his first three holes on the front nine but failed to keep his momentum going at the fourth, when he splashed out of greenside sand to just five feet.

He bogeyed the par-three sixth as well, firing a seven-iron into the heart of the green before three-putting to crash to six over par for the day.

A birdie at the seventh, where he crashed a two-iron off the tee and then rifled a lovely eight-iron to two feet was only a brief sparkle of brilliance as he dropped three shots in the last two holes.

Caddie Foster, added: "He is just playing with zero confidence. He is swinging it better but once it comes to the tournament it is not happening."

South African Ernie Els birdied his first two holes but dropped six shots in as many holes in the middle of his round for a two over 72.

Els said: "It's nice to see John (Daly) up there. It's amazing. This golf course doesn't suit his game at all and it's nice to see him up there at the top of the leaderboard.

"Amazing. Anything under par he is a good score. If you miss a shot in the rough you have a 50 percent chance to get a par. But in the same breath there is a chance to make a double.

"The ball stops on the green and if you play proper golf you can score well."

Spaniard Sergio Garcia looked set to bounce back after his Open tragedy when he got to three under after four holes.

But he was disappointed to card a level par 70 after dropping shots at his last two holes - the eighth and ninth.

He said: "It is not a bad round but it was a nice way of throwing a good round in the trash. Just a shame those two bogeys on the last two.

"It's really hot. You have to constantly clean the sweat off your arms and hands and 15 seconds later you are sweating again. So it's not easy."