Stephen Kenny admitted the manner of defeat for his St Patrick's Athletic side at Tolka Park was a "tough one to take".
The Saints had made a good start to the Dublin derby against reigning champions Shelbourne on Friday night with Mason Melia opening the scoring.
But the tables were turned in the second period as Shels equalised early in the half via Harry Wood before Kerr McInroy scored a late, late winner for Damien Duff's side.
Speaking to RTÉ Sport's John Kenny after the 2-1 defeat that leaves Pat's four points off the summit in a congested top end of the SSE Airtricity Men's Premier Division table, former Republic of Ireland boss Kenny rued how the second half played out.
"First half we were brilliant, obviously we were disappointed to be just one up," he said.
"We had a few other chances, we could've maybe with a better final pass created even more chances.
"But obviously the goal a minute into the second half was a turning point, Chris Forrester got a bad injury and was lying down so we were down a man but still we should've defended better than we did.
"And it was quite end to end then, it felt, and we played quite a lot of good football. Shels, obviously, tails were up and it was end to end but neither team could get that winner. But then to concede right at the death was a tough one to take."
The result also marked another loss on the road in a Dublin derby for Pat's this season and Kenny admitted that they will have to find a better balance away from Inchicore.
"We've lost away in Dublin three times but the other side of that is that at home we're unbeaten and been excellent, so we have to find a balance," he said.
Meanwhile, the victory ended Shelbourne's five-game run without a win and defender Sean Gannon, who was among a trio of players thrust into action by Duff for the start of the second half, said he was delighted by the resilience shown by his team-mates, adding that "it showed why we're champions".
"We've had a bit of a mad few weeks I suppose, we've been dominating games and then just a bit of complacency in our play and conceded goals that were uncharacteristic and sometimes you just need to keep working," he said.
"You just need to get back to the training ground, things are going against you. The belief in the group is still really high so we just work hard.
"I thought we started the game quite well and then the goal... it's hard when you're watching the game on the sideline to know if it's against the run of play or not but obviously a bit of a sucker punch for the goal.
"And look, as a sub, you just try to come on and help the group, help the team, contributing. Subs are only part of the process.
"The lads who were still playing from the first half were excellent in the second half. It's just one of them things, if you keep working hard you get your rewards.
"We've probably conceded goals late on in games and as I've mentioned, uncharacteristic, so it's nice for it to be on the other foot tonight and Kerr, who was excellent again I thought and has been unbelievable for us since he's come in, it's great to see him get the winner."
