John Joe Nevin's absence from the Ireland boxing squad for next month's World Championships in Kazakhstan has left the squad without a representative in the bantamweight slot.
Nevin was on the original list of 10 names lodged by the Irish Amateur Boxing Association with world governing body AIBA, but subsequently declared his intention to turn professional.
Ireland attempted to replace Olympic silver medallist Nevin with Gary McKenna at 56kg - only for AIBA to then rule out the switch due to the deadline for registration having passed.
The departure of world number one Nevin to the professional ranks is a blow to the Ireland squad which hopes to surpass the one bronze - won by Nevin - at the last World Championships in Azerbaijan two years ago.
Ireland head coach Billy Walsh said: "John Joe will obviously be difficult to replace. He's ranked number one in the world and would have been seeded at number one in Kazakhstan.
"But our focus is on the World Championships. John Joe is not going and the rest of the squad are, and they are our focus now."
The Ireland squad is headed by two London 2012 bronze medallists, light-flyweight Paddy Barnes and flyweight Michael Conlan - who is expected to follow Nevin into the professional ranks after the tournament.
Walsh added: "The World Championships is always the toughest tournament - tougher than the Olympic Games. But if the team perform to their potential they are capable of doing well."
Ireland squad: Light-flyweight: Paddy Barnes; Flyweight: Michael Conlan; Lightweight: Sean McComb; Light-welterweight: Ray Moylette; Welterweight: Adam Nolan; Middleweight: Jason Quigley; Light-heavyweight: Joe Ward; Heavyweight: Tommy McCarthy; Super-heavyweight: Con Sheehan.