(CNN)Rory McIlroy's homecoming turned sour Thursday as a nine-over par 80 left the world number one way off the pace at the Irish Open and struggling to make the cut for the second straight week.
Irish Open 2015: Rory McIlroy blown off course with opening 80
McIlroy is hosting the event at the Royal County Down Golf Club, but tough and windy conditions left the 26-year-old with a string of bogeys on his card to the dismay of the massive gallery following his group with U.S. Open champion Martin Kaymer and Rickie Fowler.
Germany's Kaymer also disappointed with a 79, but Fowler, playing for the first time since his Players Championship success in the United States, carded a challenging level-par 71.
Fowler and McIlroy had last trod the fairways at the famous course in Northern Ireland back in 2007 when they represented their countries at the Walker Cup, the start of an enduring rivalry.
Fowler was part of the victorious United States team that weekend and forged a friendship with McIlroy, who invited him to play in the Irish Open for the first time.
McIlroy has pledged to donate any prize money he wins to his charitable foundation, but after early missed birdie opportunities, he reached the turn in five-over par 41 and continued to drop shots on his second nine, making it a promise he is unlikely to have to keep.
His return to European Tour action, after winning two of his last three events on the PGA Tour, Fowler taking the other, has not gone to plan.
Defending his PGA Championship title at Wentworth last week, McIlroy shot a second round 78 to miss the cut.
If he fails to make the halfway cut in his latest tournament, it will also be the third straight time he has failed to play the weekend at the Irish Open, but McIlroy is determined to avoid that fate.
"I'm not sure what I'm going to need to make it into the weekend, but obviously I would love to be here for that. So I've just got to get out there and play a bit better," he told the official European Tour website.
"It's disappointing, but you know, I just need to pick myself back up and get out there tomorrow and try and shoot a good one."
McIlroy's efforts were in contrast to the superb 67 posted by another home hope, Padraig Harrington, the 43-year-old Irishman running up five birdies in six holes from the 11th in afternoon play.
Harrington, who scored a comeback win at the Honda Classic on the PGA Tour earlier this year, is bidding to add to his 2007 Irish Open victory.