Damien McGrane four-putted his final hole for a triple bogey eight and a round of 74 as the Irish made a slow start in the Open de Andalucia in Seville.
One-under par for his round with one hole to play, McGrane's third to the par-five ninth plugged in the back bunker, from where he took five more to get down.
Visibly annoyed as his fourth shot trickled down a step in the green to finish 40 feet away, he knocked his approach putt three feet past the hole but missed that one for a bogey six and then pushed his next effort past the right edge as he rushed to get finished.
McGrane finished tied for third in last week's Madeira Islands Open with Michael Hoey claiming sixth place.
But Hoey was also out of sorts in Seville as he racked up five bogeys and two bogeys in a three-over par 73.
Putting left-hand below right for the first time in Europe, Paul McGinley carded a level par 72 that included 28 putts and left him five strokes behind clubhouse leaders Colin Montgomerie, Jean-Francois Lucquin and fomer Walker Cup player Steven O'Hara.
Scotland's Chris Doak, the world No 1329, eventually took a one-stroke lead over the field with an immaculate 66.
Afternoon starter Peter Lawrie finished as the leading Irishman after a one-under par 71 at the course where he lifted his maiden European Tour title in last year's Spanish Open.
But Gary Murphy and Jonny Caldwell have work to do to make the cut after rounds of 76 left them on four-over par.