India's Jeev Milka Singh and Australian Richard Green shared the lead after the opening day of the Irish Open at Adare Manor on Thursday.

Green, aiming for a place in next month's U.S. Open, joined Singh at the top of the board with a six under par 66 in superb conditions.

The duo were two strokes clear of German Marcel Siem, Sweden's Johan Edfors, Welshman Bradley Dredge and France's [Images] Michael Lorenzo-Vera who were tied in second place on four under.

Northern Ireland's Rory McIlroy was the leading Irish player after signing off for a two under par 70 to end the round two strokes clear of defending champion and reigning British Open titleholder Padraig Harrington.

Green, 37, was returning to competition for the first time since missing the cut on his debut appearance in last month's U.S. Masters.

After slipping outside the top 50 in the world rankings, the 68th ranked Australian is competing in Ireland and next week's European Tour flagship BMW [Images] PGA Championship as a means of qualifying for the U.S. Open starting on June 12.

The Melbourne-born player will need to pick up the 18 places by the close of play in next week's event in England [Images] to be guaranteed entry into the U.S. Open at Torrey Pines.

"I was top 50 in the world rankings at the end of last year, that got me into the U.S. Masters but I've since slipped down the rankings so now I've come back to try and work my way back into the 50," said Green after a round that included seven birdies and just one bogey.

"I want to remain in the top 50 till the end of the year as it would get me back into Augusta," he added.

"If I get into the U.S. Open it will mean I am into all four Majors this year which is something I have never managed in my career before."

Singh produced a bogey-free round in his search for a first European Tour win this season to make-up for the disappointment of losing out in a play-off in the recent Ballantine's Championship in South Korea.

The Chandigarh-born player had to seek a ruling on the last hole after his third shot landed in trees and close to television cables.

After advice from a Tour official, Singh stepped gingerly towards his ball with hands in pocket before superbly punching his fourth shot out and some 40 feet past the flag from where he managed to save par.

Singh's opening round 66 matched the score he recorded on day one in 1999, the year he made his Irish Open debut.

"I've been playing really well this year and I've been knocking on the door," said the Indian. "The only thing I can do is just try, and hopefully something good comes my way."

Harrington recorded three birdies and a similar number of bogeys. "I'm not happy with the score, but I'm happy with the way I played," he said.