Conor Ferguson was an agonising 0.05 seconds outside the Olympic qualifying time in the 100 metres backstroke final at the Irish Open Championships.
The Larne swimmer, 16, cut 0.22 off his previous best, as he clocked 54.41 to set a new national record in Dublin.
Ferguson finished ahead of his Irish team-mate Shane Ryan (54.93) who has already qualified for Rio in the event.
The 16-year-old will have another chance to achieve the Rio mark when he leads out Ireland in the medley relay.
If Ferguson doesn't achieve the standard of Saturday, his next chance to achieve the time is likely to be at next month's European Championships.
Those championships start in London on 9 May.
The women's 100m Backstroke Final saw Ferguson's club-mate Danielle Hill retaining her national title in 1:04.25.