Shane Lowry vowed to keep his foot on the gas after he carded a sensational five-under 66 to finish the opening day of the Open Championship in second place at Royal Troon.

The 2019 champion shot one of just three bogey-free rounds of the day when Rory McIlroy crashed to a miserable 78 to all but kiss his hopes goodbye on a day of stiff southerly winds.

The Offaly man held the clubhouse lead for an hour before the unheralded Englishman Dan Brown made an eight-footer for birdie at the 18th for a six-under 65.

Brown had missed six cuts and withdrawn once in seven starts before making the cut and finishing 61st in last week’s Scottish Open.

Ranked 272nd in the world, he won the ISPS Handa World Invitational at Galgorm Castle last year and showed no signs of the knee injury that sidelined him for seven weeks earlier this year as he matched Lowry and Justin Rose, who shot 69, by carding just the third bogey-free round of the day,

“It’s just hard to get there,” Lowry said after his lowest opening round in a major. “Going against the best golfers in the world, it’s hard to get to the front.

“When you do get to the front, you kind of have to keep going and keep your foot down, and yeah, see where it leaves you at the weekend.”

Lowry made 128 feet of putts in a superb performance on the greens, and the crowd was so excited that he said it felt like Sunday as he walked down the 18th and holed a five-footer for his fifth birdie and a two-shot clubhouse lead over Justin Thomas.

“The walk down 18 was actually pretty cool,” he said, recalling his 2019 win at Royal Portrush.

“I said to Billy Foster, we walked down beside each other, and it’s the greatest walk in golf, and I got to do it on a Sunday afternoon with a full house, and that’s the plan, to try to get to do that again.”

While the switch in wind direction was forecast for round one, Lowry dealt with it better than most having visited Troon for two days a fortnight ago.

“Yeah, it did change a lot because we played the front nine down and the back nine into the wind in all our practice rounds,” he said.

“But fortunately enough, I came here two weeks ago, and I played this wind on the second day that I played here. I saw the golf course in every wind possible I could see it.

“I guess that was a good thing to do, and it’s after paying off a little bit today.”

Meanwhile, Galway amateur Liam Nolan found himself tied with McIlroy, but not how he would have wished, after making four bogeys and a triple bogey seven at the 13th en route to seven-over 78.