Paul Dunne is the joint leader at the Open de Espana after an opening round of 66 in Madrid.
The Greystones man is level with Scot Marc Warren on six under par after superb back nine that featured three birdies and an eagle on the par-five 18th.
"I find the greens quite tricky to read, especially on the front nine, so it was nice to get a couple of putts to go in on the back nine and climb up the leaderboard," Dunne, who won the British Masters last year, told Sky Sports.
Gavin Moynihan was level par after a 72, despite a quadruple bogey on the fifth.
World number four Jon Rahm is one of 11 players a shot behind Dunne and Warren.
Job well Dunne.@dunners11 eagles the 18th to card an opening round 66. pic.twitter.com/6wnPnYjWFG
— The European Tour (@EuropeanTour) April 12, 2018
Rahm, who finished fourth in the Masters on Sunday, carded an eagle, four birdies and a solitary bogey at the Centro Nacional de Golf, where he practised during his amateur days.
"It feels great," Rahm told Sky Sports. "To be honest I would have taken anything under par given the fact that I played better than I expected, especially off the tee. My long game was amazing.
"The driver alone set up two birdies today on 13 when I hit it over the green and seven where I hit it to the front edge of the green. Things like that are obviously a bonus. Hopefully I can keep hitting it tee to green the same way and make a few more putts the rest of the week."
Asked how he was feeling following the trip across the Atlantic, Rahm added: "The morning is not as bad as the afternoon. When jet-lag kicks in after the round and adrenaline goes the afternoon is a little harder.
"I'm a lot better than I expected and hopefully it keeps going because sometimes jet-lag tricks you. It gives you a good day and the next day is horrible."
Jon Rahm's round 1 highlights 🎥#OpendeEspaña pic.twitter.com/MGkDEyM6wC
— The European Tour (@EuropeanTour) April 12, 2018
