David Howell turned back the years to take a one-shot lead after the first round of the Irish Open but last year's runner up Robert Rock was disqualified after a scorecard mix-up.

Howell hit five birdies and an eagle in his seven-under-par 64 but Rock had fired a 65 before tournament officials discovered he had mixed up his scores on the 14th and 15th holes at the Killarney Golf Club.

Thirty-five-year-old Howell, who had been ninth in the world rankings four years ago, started this tournament 479th and admitted after his round that he had thought about quitting the game recently.

"I've never wanted to give up, but it's crossed my mind that if I'd carried on playing as I did last year, I wouldn't have a career to be worried about," he admitted.

"It was nice not to drop a shot. I haven't done that for a long time but I holed a few bombs today.

"I chipped in and I think I holed three long ones as well. As it happens, I had a few more chances that I missed but I certainly holed more than my fair share, which in fairness you normally do when you shoot a 64.

"I just haven't got off to a good start all year. Obviously I've not been playing well, or as well as I know I can, but my form has not been that bad.

"But it's pretty hard to make cuts out here when you shoot 73 in the first round. It puts you under added pressure and I've been dying to get off to a nice start. That finally happened today."