Rory McIlroy admitted “too many stupid mistakes” prevented him from making a strong start to the Open Championship as a rollercoaster opening round of 72 left him seven shots behind surprise leader Jackson Suber.

Hoping to add a second Claret Jug to the second Masters title he claimed in April, McIlroy endured a frustrating day on Royal Birkdale’s greens during a round that featured four birdies and six bogeys.

The six-time major winner missed three four-foot putts in the space of four holes from the seventh before mixing three birdies with two bogey sixes over his final six holes.

“The two bogeys on the par-fives weren’t great and I struggled the first two holes to get the speed of the greens,” said the 2014 Open champion, who felt he drove the ball well after driving the green of the 415-yard ninth hole.

“I felt like they were very inconsistent, just because some parts of the greens are still alive and growing and other parts are really dead.”

McIlroy, who finished joint fourth at the 2017 Open at Birkdale, added: “[I] sort of felt like I got it going a little bit, but just too many stupid mistakes. But every time I made a stupid mistake, thankfully I made a birdie to sort of keep myself in it.

“[I’m] not too far away. Hopefully we’ll get the better conditions [on Thursday] and maybe the greens are a little bit smoother in the morning.”