Michael Conlan suffered an upset defeat in his Belfast hometown when he succumbed on a split decision to Kevin Walsh.
Conlan, a two-time Olympian and London 2012 bronze medallist, still harboured ambitions of a world title fight after Walsh.
But he suffered a points loss at the SSE Arena in Belfast.
One judge had Conlan winning their 10-rounder 97-93 but the other two officials both scored 96-94 for Walsh.
Unbeaten American Walsh, from Brockton, Massachusetts, rose to the occasion to secure the best victory of his career so far.
"It was a close fight," Walsh said. "But I got it done."
Conlan turned professional in a blaze of publicity and did fight his way into world class. His extraordinary clash with Leigh Wood in 2022 ended in a knockout defeat.
In 2023 he challenged Luis Alberto Lopez for the IBF featherweight world title but also lost by stoppage. An upset loss to Jordan Gill back in 2023 as well was a heavy blow to his career.
He was rebuilding, impressing with last year's knockout victory over Jack Bateson for instance.
But this latest defeat is a major setback. Rather than pressing for a world title shot, now the 34-year-old might have to consider his future in the sport.
