St Nicholas Abbey's comeback after a year away ended in disappointment when he finished third at the Alleged Stakes at the Curragh.
The Aidan O'Brien-trained 4-11 favourite had not raced since last year's Newmarket 2,000 Guineas.
But the 2009 European champion juvenile faded in the final quarter-mile as Unaccompanied, ridden by Pat Smullen, won the race from 33-1 outsider Cilium.
"They quickened up at halfway and he got a little bit tired," said O'Brien.
"It was his first time back and it was just to get him started again. It was a good while since he ran and he got a little bit tired in [jockey] Seamus' [Heffernan] hands.
"It's very early in the season and it's very hard to have a horse peak fit on that kind of ground if you are thinking about going on for the rest of the season.
"We've got him started now and hopefully we'll look forward to his next run."