Martin O’Neill says Celtic supporters are right to feel frustrated after watching another European night slip away at Celtic Park.

For a short spell after the goal, Celtic looked as if they had put themselves in a position to win the game. Liam Scales then hit the bar from a corner, and that proved to be a big moment.

Celta levelled through Javi Rodriguez from a free-kick before the same player struck again from distance only minutes later.

Celtic could not find a way back, and by the closing stages, some supporters had already started making for the exits.

Asked about the frustration among the support, O’Neill said: (BBC Sport), “Well, I’m not checking that part of it, so I don’t genuinely know.

“But of course, the supporters will be frustrated as well, too.

“Because when you try and do your best in European football, because that’s what you strive for. This is the whole point.

“You spend the whole domestic season trying to get into European football.

“And you want to do your best. You want to do your best for the team.

“And you want to do the best for the club.”

That is the part that will sting for supporters.

Celtic spend every domestic season chasing the platform to play in Europe, but the first three league phase games have brought no points.

The table is now ugly. Celtic sit second bottom with three defeats from three, and the idea of rescuing the campaign already looks like a huge ask.

The frustration is obvious because Celtic had the game in their hands at 1-0 and still found a way to lose it.

Scales hitting the bar may be pointed to as a big turning point, but the bigger issue came after Celta equalised. Celtic lost control, failed to clear properly, and were punished by Rodriguez’s second goal.

Supporters can live with a hard game. What they will struggle to accept is seeing the same European problems appear again.

Sunday at Easter Road now becomes about response, but Celtic’s European campaign is already in serious trouble.