But Evan Ferguson levelled on the night with a superb 63rd-minute finish. And Celtic striker Idah finished the job off in the 84th minute with a close-range volley from Mark Sykes’ cross.
Jake O'Brien was denied early on by keeper Plamen Iliev's save. But as promising as their start had been, Hallgrimsson's side were undone the first time Bulgaria launched a meaningful attack.
Kiril Despodov delivered a 30th-minute corner towards Georgi Milanov and when the playmaker's volley was blocked, Antov was on hand to finish from six yards.
Irish confidence seemed to take a hit. But Troy Parrott then came close but his headed effort landed on the roof of the net.
Two minutes before the break O'Brien again came close from a Brady corner but his header lacked power and cleared off the line by Simeon Petrov.
Mike...