Clarke was alongside world number one Tiger Woods in second while out on course Sergio Garcia was also five under with five to play.

Woods would have shared top spot but for a bogey on the 400-yard 17th, where he missed from under six feet after coming up short with his approach.

Like Curtis, Clarke did not have a bogey on his card.

“I played very nicely,” he said. “I’m not saying this course is easy, but it’s a bit of relief after last week, which was brutal.” Clarke missed the halfway cut in the US PGA Championship at Oak Hill, as did Curtis and Garcia.

It was not the most promising of starts when he hit a tree with his drive on the 497-yard second and finished on the adjoining third fairway. But a 50-yard pitch to eight feet still enabled him to birdie the hole and he was off and running.

Further birdies came on the third, fifth, 10th and 12th and a massive drive on the long 16th gave him hopes of another.

Clarke had 276 yards to get to the front of the green and, even with water in front, took a three-wood out of his bag three times and thought about going for it.

Eventually he decided not to and was left wishing he had when he pitched into sand over the green. But he saved par and scrambled fours on the two closing holes.

Curtis, who is getting married after the event, admitted he went out with an attitude of “good or bad I don’t care – this will be the best week of my life no matter what I shoot”.

Woods showed his liking for the lay-out again from the time he birdied the second. It is now nine sub-70 rounds in a row on it and, even if he does not have a major to his name, he remains the man to beat.

Garcia eagled the second and then had four successive birdies around the turn to join Curtis. The 23-year-old had a bogey on the short 12th, but finished with a 20-foot birdie putt.

Colin Montgomerie was content enough with his two under 68, saying: “It’s important to make a decent start and that is. But father-to-be Padraig Harrington admitted he thought about pulling out en route to his 73.

“I spent most of the day wondering whether it was time to go home,” said the Dubliner. “But I think that would be wrong. This is a big tournament and it deserves respect.”

He blamed a swing change rather than the distractions of parenthood for his score, though.

“I hit half the shots as well as I could and half as bad as I could. Get in position on this course and you can make birdies, but when you get out of position there’s a good chance of bogeys. It’s a good test.”

Paul McGinley and Lee Westwood both returned 70s – and for Westwood that was miserable.

Four under par and sharing the lead after 16 holes he triple-bogeyed the 17th and bogeyed the last.

“What can you do?” he asked. “Can you give me anything to be optimistic about after that?”

His annoyance was mainly at his drive down the 400-yard 17th, which caught the top of a bunker – and stuck there.

“I pushed it a little bit right, it pitches in the face of the trap and when I get up there I can see about three dimples of the golf ball,” he added.

Unable to get it out of the bunker Westwood then had a fresh air shot from the rough by the green and in the end had to make a five-footer just to drop three shots.

Ian Poulter was critical of the sand in the bunkers as he shot 73, while fellow Englishman Phil Golding, in the field because of his French Open win in June, had a triple bogey eight at the 16th in his 76.

Justin Rose, Paul Casey, Phillip Price and Nick Faldo were among the later starters.

Price was one under after 10, but Rose and Faldo were two over after 17 and eight holes respectively and Casey four over with five to play.