Shane Lowry is a shot off the lead at the 152nd Open Championship, while a disastrous opening round 78 leaves Rory McIlroy in line for an early exit at Royal Troon.
The Offaly man hit the lowest opening round in a major of his career with a five-under 66 and the first bogey-free round at The Open since the third round in 2019 when he won at Royal Portrush.
However, it is England's Daniel Brown who leads the way; birdies at 16 and 18 saw him take outright lead as darkness drew in at the Ayrshire venue.
"It was enjoyable. I got off to a bit of an iffy start and holed a couple of nice par putts early on and then I was off and running," Lowry told Sky Sports.
"I holed a putt to go into the lead and I thought 'It's the first time I’ve led The Open in five years’."
Asked whether he was playing as well as 2019, he added: "I’ve no idea. I managed to roll a few putts in and I always say if I keep holing putts putts I can be dangerous."
McIlroy recovered from a bogey at the first to reel off six consecutive pars and stay in contention early on.
But he proceeded to find trouble for the rest of his round.
At the par-three eighth hole, nicknamed the Postage Stamp for its small green, McIlroy found a bunker off the tee.
On his first attempt to punch out, the ball trickled back down the slope into the sand.
After taking double bogey there and bogey at hole 10, McIlroy drove out of bounds at the par-four 11th and incurred another double bogey.
Two more dropped shots at 15 and 18 left him on seven over par overall.
"The course was playing tough," McIlroy said. "Conditions were very difficult in a wind that we have not seen so far this week.
"When that happens it presents different options and I didn't adapt well enough to the conditions."
Justin Thomas is back in third after the American birdied his final two holes to shoot a three-under 68.
Alex Noren of Sweden, Nicolai Hojgaard of Denmark, Justin Rose of England and Russell Henley posted two-under 69s earlier in the day.
Padraig Harrington posted an excellent 72 to sit on one-over, with Tom McKibbin a shot back
Darren Clarke record a six-over 77 while Galway amateur Liam Nolan endured a tough finish as he fell to seven over with a treble bogey on the 13th hurting.
Former champion Tiger Woods is unlikely to make the weekend after an eight-over 79.
