Former world number one Thomas, sporting a pair of tartan trousers, said a sub-60 round had been in his thoughts after he covered the first 13 holes in eight under.

The American, who was among the later starters, drained a 13-foot putt for an opening birdie then reeled off four in a row from the fifth to reach the turn in 30.

Three more birdies – including a 42-foot putt on the par-three 12th – followed in the next four holes before the run dried up just as he was eyeing a 59.

“Honestly, I thought the par was 71 and then I looked up and saw even-par 70 and I was like, ‘I just need a couple more [birdies] and I can shoot 59,'” Thomas said.

“Then, shocking, I made five pars in a row.

“I definitely wanted a 59 and was even thinking a couple lower, so we all know how that works out when you get ahead of yourself.”

Earlier, McIlroy, starting on the 10th, began with a birdie but immediately dropped a shot after twice finding heavy rough.

Bogeys on 14 and 16 bookended a birdie in an untidy front nine for the world number two in which he hit only three of six fairways.

But he came alive after the turn, with a birdie on the first followed by a delightful chip-in eagle from the right-hand side of the par-five third.

He picked up another shot at the next and chances for further birdies from inside 11 feet slipped by on five, six and nine.

“Obviously the last time I played, I played well. I didn’t get the result I wanted but I’ve still got a lot of confidence in my game,” said McIlroy.

“I shot a solid score today. I gave myself plenty of chances on that back nine and actually felt like I left a couple out there as well.

“It was as gettable as you’re going to get this golf course. Hopefully no more rain over the next few days and the wind can get up a bit and the course can start to play a little bit tougher.”