Newcastle, Northern Ireland (SportsNetwork.com) - Padraig Harrington and Maximilian Kieffer carded 4-under 67s on Thursday and were tied for the lead after one round of the Irish Open.

Harrington won this title in 2007 at Adare Manor Hotel & Golf Resort and is a three-time runner-up as well. Kieffer, who is making his 13th European Tour start of the season, has two top-10 finishes and is looking for his first tour win.

Soren Hansen, the 2002 winner, is one stroke off the lead at minus-3 at Royal County Down Golf Club. Danny Willett, Soren Kjeldsen and Emiliano Grillo share fourth place at 2-under 69.

Former world No. 1 Luke Donald posted a 1-under 70. He was joined in seventh place by Matt Ford, Rikard Karlberg, Chris Wood, Alexander Levy, Anders Hansen and Trevor Fisher, Jr.

Current world No. 1 and tournament host Rory McIlroy struggled to a 9-over 80 in cold and windy conditions. He carded nine pars and nine bogeys in his opening round. That was his worst score since carding an 80 in the final round of the 2011 Masters.

McIlroy had a bogey and four pars in his first five holes. He stumbled to four straight bogeys from the 15th. On the front nine, McIlroy bogeyed four of five holes from the fourth to slide to plus-9. He parred the ninth and finished the opening round tied for 150th.

"It was not quite as difficult as I made it look," joked McIlroy. "It's disappointing because I want to go out there and play well, not just for myself, but for a lot of other people. I'll just have to pick myself up and go out there tomorrow and shoot a good one."

Harrington, who played alongside five-time Ryder Cup teammate Sergio Garcia and defending champion Mikko Ilonen, birdied the first, but gave that right back as he bogeyed No. 2.

The Irishman dropped a shot at the fourth, but erased that mistake with a birdie at the sixth. He parred the next three holes to make the turn at even- par.

Harrington stumbled to his third bogey of the day at the 10th. He bounced back with a birdie on No. 11. Harrington also birdied the 12th and 13th to move to minus-2.

After a par at 14, Harrington moved into the lead with back-to-back birdies at 15 and 16. He closed with a pair of pars.

"After nine or 10 holes I thought to myself 'C'mon, we've got to hit a good shot, no need to be afraid,'" said Harrington, who withdrew from the BMW PGA Championship last week with a shoulder injury. "I know from experience now that I'm in a position where there's many ways of competing in this tournament. I've two options - play great from now on and try and get away from the field or play average and fight it out on Sunday afternoon."

Kieffer, who was in the last group out off the 10th tee, parred his first two holes before making eagle at the par-5 12th. He gave both of those strokes back as he tripped to bogeys at 13 and 15.

The 24-year-old German atoned for those dropped shots with birdies at 16 and 17. Around the turn, Kieffer birdied the first and third to join Harrington in the lead at minus-4.

Kieffer briefly moved in front with a birdie at the par-4 sixth. However, he faltered to a bogey on the eighth to drop back to minus-4, and he ended there after a par at the ninth, his last.

NOTES: Harrington's last win in Europe was at the 2008 Open Championship ... Rickie Fowler (71) and Martin Kaymer (79) played alongside McIlroy ... Willett, Fowler and McIlroy played at the 2007 Walker Cup at Royal County Down ... Garcia and Ilonen are tied for 90th after shooting 4-over 75.