Open champion Darren Clarke missed the cut at the Irish Open with fellow major winner Padraig Harrington also making an early exit in Killarney.
Clarke's 74 left him one over while Harrington's poor recent form continued as a 72 put him on three over.
Northern Ireland amateur Paul Cutler is six under - four behind leader Marcel Siem - while Rory McIlroy is six off the pace.
Graeme McDowell joined McIlroy on four under after an impressive 66.
German Siem leads on 10 under after an eagle 16 and birdie on 17 helped him card his second successive 66.
Siem leads first-round leader Jeev Milkha Singh and Dane Soren Hansen by one shot while Spain's Ignacio Garrido is a further stroke back.
Indian Singh followed his opening 63 with a steady 70 while Hansen shot a 66.
Defending champion Ross Fisher is in a group on seven under which includes other Englishmen Simon Wakefield and Simon Dyson.
Portstewart amateur Cutler, Michael Hoey and another Irishman Damien McGrane are among those on six under.
After his opening 69, Clarke moved up the leaderboard after birdies at the first and third before his momentum was halted by bogeys on the fourth and fifth.
While the Dungannon man picked up a shot at the sixth, three straight dropped shots from the 11th left him battling to make the cut and a further bogey at the last sealed his fate as he missed out by two shots.
"All in all, I'm disappointed with my score but there's always next week," said Clarke, referring to the WGC Bridgestone Invitational event in Ohio.
Harrington, after his opening 73, briefly raised his hopes with a 15-foot birdie putt on the first and then a marvellous par-save at the second.
However, the Dubliner double-bogeyed the short sixth, dropped another on the long next and failed to produce the necessary heroics on the back nine which contained a bogey at the 10th and solitary birdie on the 16th.
In contrast Cutler, 22, produced a hugely impressive round of five birdies and only one dropped shot.
The Walker Cup candidate, who started his opening round with an eagle two at the first, said that his performance over the first 36 holes had been "way above my expectations".
Inevitably, there is now talk whether Cutler can emulate Shane Lowry's Irish Open triumph as an amateur two years ago.
"It would be silly to think I can win it. (But) Yeah, why not?" said Cutler.
McIlroy, after his Twitter spat with golf pundit Jay Townsend on Thursday, was in danger of missing the cut as he dropped back to level par after seven but four birdies in his closing 10 holes left him only six off the pace.
The US Open champion remained unrepentant about his row with Townsend which came after the American criticised his course management in Thursday's round.
"I don't really have any respect for the man," said McIlroy.
McDowell regrouped well from his opening 72 to hit a six-birdie 66.