Rory McIlroy admitted he was uncomfortable as the world number one struggled during the RBC Heritage first round on Thursday.

McIlroy battled to a one-over 72 at Harbour Town Golf Links in South Carolina to be well off the pace at the PGA Tour event.

The four-time major champion, playing the tournament for the first time since 2009, said it was hard to get comfortable during the opening round.

“I think just my overall comfort level. I wasn’t particularly comfortable out there,” the Northern Irishman told a news conference.

“I played here once before in ’09, and I just can remember not being that comfortable around here then, and it’s still sort of the same.

“I’m just not comfortable and sort of trying to pick lines and really commit to shots. I just wasn’t as committed as I need to be around here.”

McIlroy mixed three bogeys with two birdies to be left back in a tie for 101st after the first round.