Richard Green was in excellent form in Thursday's opening round

Australia's Richard Green and India's Jeev Milkha Singh carded six-under-par 66s to lead the Irish Open after the opening day at Adare Manor.

As several big names struggled, the pair secured a two-shot lead over a group which included last year's runner-up Bradley Dredge.

Rory McIlroy is the leading Irishman at two under, while holder Padraig Harrington and Darren Clarke shot 72.

Britons Colin Montgomerie and Lee Westwood could only manage 75.

After starting at the 10th, Singh's round included an eagle three at the seventh, thanks to a fine three wood which landed a foot of the pin.

The former Volvo Masters champion looked certain to drop a shot at his final hole when he found a bush, but he rescued his par by holing a brilliant 40-foot putt.

It was probably the easiest day you'll ever get on this course in terms of weather Padraig Harrington

"My backswing was about a foot-and-a-half and I was more worried about just hitting the ball," said Singh of his escape from the bushes. "It could have gone anywhere."

Green, who was fourth in last year's Open, hit eight birdies in his first competitive round since missing the cut at the Masters.

"I concentrated on concentrating hard and it worked out pretty well," said the left-hander.

Holder Harrington lamented a few "mental errors", which included finding the water with his tee shot at the spectacular 18th hole.

"I suppose 72 doesn't look that good when you see six under, but that won't have played me out (of contention) at this stage," said The Open champion.

"But it was probably the easiest day you'll ever get on this course in terms of weather and so there was an opportunity out there."

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Recent Asian Open winner Clarke was one under after 10, but struggled on the back nine and he was fortunate to bogey the 17th after a hooked tee shot and topped second.

However, a closing birdie enabled Clarke to finish level as he signed for a 72.

Montgomerie, whose slip to 88th in the world this week represents his lowest position since October 1990, ran up a seven on the long seventh and he faces a battle on Friday to make the cut.

Like Harrington, Westwood also struggled on the 18th hole as also finished on 75, while another Ryder Cup contender, Martin Kaymer, is 11 shots off the pace.