Rory McIlroy admitted to feeling “a little lost” as he struggled to a first round of 74 in the Irish Open that left him eight shots off the lead and battling to make the cut.

McIlroy won five times last year, including his second Major title in the US PGA Championship at Kiawah Island, but has struggled to reproduce that form in 2013.

The 24-year-old finished 41st in the US Open at Merion a fortnight ago and yesterday apologised for throwing a club and bending his nine iron out of shape during a final round of 76.

The nine iron – one of the Nike clubs he controversially changed to in a multi-million pound deal in January – has since gained a new shaft, but that did little to improve his fortunes at Carton House, where Sweden's Oscar Floren carded a six-under 66 to lead by one from former champion Shane Lowry, Michael Hoey, Joost Luiten, Peter Uihlein and Jean-Baptiste Gonnet.

Lowry, who was still an amateur when he won at Baltray in 2009, was playing alongside McIlroy – whom he beat in the first round of the Accenture Match Play in February – while the third member of the group, the in-form Thomas Bjorn, carded a 68 that was matched by the likes of Paul Casey and former Ryder Cup captain Jose Maria Olazabal.

McIlroy cut a disconsolate figure after his round and there was a long pause when he was asked what was going wrong.

“I don’t really know,” the world number two said. “No aspects of my game are standing out as strong. I’m hitting it well on the range and struggling hitting shots out on the course. The game is not coming as easy to me as it did last year.

“Off the tee I’m missing it left and right and it’s difficult to stand on the tee and be confident that at least one side is out of play. I don’t know if it’s a case of playing through it or grinding it out on the range.

“I just feel a little lost at the moment. I had a good chat with my dad and Michael Bannon (his coach) the Saturday night of the US Open and felt like we got a bit of direction from there, but it’s tough when you have rounds like this or you have tournaments where you think you’re getting somewhere and all of a sudden you’re stopped in your tracks and you’ve got to re-assess everything again.

“I’m staying patient and I don’t want to say I’m accepting this, but there’s nothing else I can do apart from trying to play well, practise and try to hit better shots.”

Lowry, starting on the 10th tee, recovered from a pulled opening tee shot which caught a bunker. It ultimately led to a bogey but he proceeded to turn in three under regulation figures with three successive birdies from the 13th to the 15th and another at the par five, 18th. He negotiated a blemish free journey over his back nine, throwing in a brace of birdies at the fourth and eighth.

Lowry admitted: “It’s great to shoot five under today and it great to be up at the top of the leaderboard but there are three rounds left. The momentum from Germany I’ve definitely brought into this week. I played decently in the practise round on Tuesday and played pretty much flawless golf yesterday in the Pro-Am.

“You know, there were quite a few people watching and I was trying not to go too low in the Pro-Am yesterday because I knew everyone would be shouting about and I didn’t really want that and I didn’t really want too much hype. Yeah, playing well but there’s still three days left.

“The crowd from home are great and I’m sure there’s going to be quite a few coming up tomorrow and for the rest of the week. It’s great to have them here and you know it’s a pleasure to be out there dealing with people from home cheering you on.”

Lowry has the benefits of home advantage this week as he owns a house on the course, but revealed: “Family are banned from the house until Sunday afternoon.

"I always hang out with Graeme Storm and Oliver Fisher and when the tournament was announced I said they could stay with me. I'm trying to keep my routine as normal as possible this week.

“It would seem like there should be more pressure on me this week, but I’m looking at it as an advantage. I play this course week-in, week-out and know it like the back of my hand.

“I went to Baltray just happy to be there and would have been happy going home with four rounds under my belt, but obviously I came away with a lot more than that. This week and 2009 is like chalk and cheese. You can say I’m coming here trying to win the tournament but I’m trying not to talk too much about it.”

Hoey was amongst the afternoon starters and carded six birdies and a bogey to join Lowry on five under.

Limerick's Cian McNamara was a shot further back after a round that included three birdies on his back nine, while Waterford's Séamus Power had an eagle on the fourth on the way to a three-under, a score that was matched by Simon Thornton.

Ryder Cup captain Paul McGinley shot a two under 70, while Gareth Maybin and Pádraig Harrington both shot 71 to complete the Irish golfers under par.

Fresh from making the cut at the US Open, Kevin Phelan leads amongst the four amateurs taking part after carding a level-par 72, with Gavin Moynihan on one over.