Greystones' Paul Dunne birdied two of his last four holes to salvage a two-over 73 in the opening round of the World Golf Championships-Mexico Championship.
The Wicklow man (25) didn't find it easy to hit fairways at the tight Mexico City track, finding just three to finish last in the 64-man field for Strokes Gained from the tee.
Despite that, he still managed to finish in the middle of the field for approach play and shares 49th place at Club de Golf Chapultepec, nine shots behind South Africa's Louis Oosthuizen.
The former Open champion carded a seven-under 64 to lead by a shot from another European Tour debutant in Chris Paisley, Tour championship winner Xander Schauffele and India's Shubhankar Sharma with Spain's Rafa Cabrera Bello and Thailand's Kiradech Aphibarnrat a further stroke behind.
Given the altitude and the tight nature of the course, it was no surprise that European Tour regulars did well.
Oosthuizen made a perfect start with close-range birdies at the first and second, before converting from 16 feet at the fifth.
Further gains came from six feet at the tenth and 12 feet at the 12th, before the former Open Champion hit a stunning approach to four feet on the par five 15th to set up a simple eagle putt which enabled him to post the first round lead.
Sharma and Paisley were particularly impressive during round one. Both men are making their World Golf Championship debuts this week, after superb starts to 2018 on the European Tour.
Sharma is the only man to have won twice on the 2018 European Tour so far after his victories at the Joburg Open and Maybank Championship while Paisley won the BMW SA Open and followed that result with top-five finishes in Abu Dhabi and Dubai to move to sixth place in the Race to Dubai.
Starting on the back nine, Dunne overshot the green with his third from the rough at the par-five 11th, failing to get up and down, then paid for a poor tee shot at the 12th with another bogey.
Another shot went at the 14th, where he was never in the fairway and missed from six feet for par.
He was unlucky not to make an eagle two at the 16th, where his 137-yard approach spun back but lipped out, leaving him a tap-in.
Out in two-over, he couldn't pitch and putt for birdie at the driveable first and promptly bogeyed the short third and the 499 yard fourth after missing both tee shots right.
But he eventually made 16-footer for birdie at the 615-yard sixth, got up and down from greenside sand at the eighth to save par and finished off his day with a 12 footer for birdie at the ninth.
Oosthuizen was pleased with his round and pointed to his driving as key.
“I'm very confident with my driver at the moment," he said. "Had a night little cut going with it, nice just aiming it a little left and just swing away.
"I've been swinging it pretty good the last three, four weeks. Felt I played really well last week, just got caught in the Bear Trap a little bit.
"Yeah, I'm hitting it well and just need to do the same tomorrow. You know, the greens can be a little bumpy at the end of the day, but I hit a few really close.”
World No. 2 Jon Rahm, playing with defending champion and world No. 1 Dustin Johnson (69) and World No. 3 Justin Thomas (72), fired the best score of the trio with a four-under 67.
Phil Mickelson, at 47, the oldest player in the field this week, opened with a two-under 69 to share 13th with Bubba Watson, who got to seven-under after 11 holes before dropping five shots in seven holes.
Seven players have made a World Golf Championships event their first PGA TOUR win, including Darren Clarke (2000 Dell Match Play) and Shane Lowry (2015 Bridgestone Invitational).
Dunne needs to finish solo second to move into the top 50 in the world and potentially secure a place in the Masters while solo fourth would put him in position to play in the WGC-Dell Technologies Match Play in Austin later this month.
Rookie Gavin Moynihan admits he’s struggling to find form after an opening 75 left him in danger of a sixth straight missed cut at the Tshwane Open in South Africa.
The Mount Juliet touring professional (23) mixed three birdies with seven bogeys in a four-over-par round at Pretoria Country Club and lies five shots outside the projected cut mark in his sixth start since winning his European Tour card last year.
"My game is just not there at the moment," the Dubliner confessed. "I'm just struggling to put 18 holes together."
Louis de Jager (30) shot a bogey-free, seven-under par 64 to lead by a stroke from a host of experienced tour winners in fellow South African Thomas Aiken, Chilean Felipe Aguilar and American Julian Suri with Moynihan tied for 143rd.
"For us South Africans this is big," said de Jager, who knows a win would secure his European Tour card. "They are all important.
"Everybody knows without you having to even talk about it and everybody knows what they are playing for. So it just motivates you more."
South Africans Shaun Norris and Combrinck Smit share fifth place after five-under 66s with another 17 players at four under including 2015 champion George Coetzee.