South Africa duo Trevor Immelman and Retief Goosen led the way after the first day of the European Open at the K Club in Straffan on Thursday.
GB & Ire unless stated
-6 T Immelman (SA)
-5 F Delamontagne (Fr), R Goosen (SA)
-4 J Lomas, G Murphy
-3 J Donaldson, G Storm, B Rumford (Aus), G Havret (Fr), D Clarke, R Chapman, N O'Hern (Aus)
Immelman's six-under-par round of 66 was sealed by a last hole birdie, to put him one ahead of playing partner Goosen and Francois Delamontagne.
Jonathan Lomas and Ireland's Gary Murphy, on four-under, share fourth.
Darren Clarke, returning after spending time with wife Heather who has cancer, was in a group one shot behind them.
Having failed to qualify for the US Open, Immelman took a two-week break from the European Tour to practise his putting at home in Florida - and it showed as he notched up seven birdies.
Clarke admitted family matters had distracted him from his game, but said he was glad to be back on the course again.
"She wanted me to come back playing again, so I'm here trying to do as well as I can," he said.
"It was good to get out and play again. I didn't get annoyed as I probably would have - my thoughts were waving a little bit.
"It does give you a bit of a boost knowing you have played well here."
Clarke, who also has a knee problem, did get to four under but found water on the eighth hole - his 17th.
Goosen started the opening round at the K Club with three birdies in his first four holes, and a 35-foot eagle putt at the 18th, his ninth, put him two clear.
However, he had nine straight pars on the front nine while Immelman came home in 32 to take the lead.
It is a major improvement from the US Open for Goosen, who slumped to 11th place after starting the final day three ahead of the field.
"I'm fine about what happened at the US Open," said Goosen, who eventually finished eight shots behind winner Michael Campbell. "Everybody else seems to be more worried about it than I am.
"It was a bad first 12 holes and from there on I was just really trying to get the ambulance back to the clubhouse.
"A lot of people have said 'bad luck', but there's no bad luck. I just played bad and end of story. Nothing like that is going to bother me."
Campbell, playing in his first event since the US Open victory, could only claim a two-over 74.