Sligo Rovers boss John Russell felt the "magic of the cup" was at play as his side recorded a 1-0 win away at Bohemians.
Rovers keeper Sam Sargeant saved a second-half penalty shortly before Owen Elding scored the only goal of the game at Dalymount Park.
The Gypsies piled on late pressure but the Bit O'Red held on to progress to the last eight of the FAI Sports Direct Cup.
"Delighted to be in the next round, not only the result but our performance, I thought we were electric in that first half," Russell, whose side sit second from bottom of the Premier Division, told RTÉ Sport.
"Some of our play was top level, the combinations, the movement... we were calm in our build-up and I don’t think Bohs laid a glove on us in the first half.
"The disappointing thing was coming in at half time not being in front."
On the crucial moments after the break, he said: "It’s the magic of the cup, I suppose.
"You want your big players to stand up and Sam Sargeant has been unbelievable for us this season and comes up and makes an incredible save.
"He’s shown his class over the last couple of weeks.
"Then we go up the other end and, for me, the best young talent in the country, Owen Elding, he was outstanding tonight, and once he got in in the box, we knew he was going to hit the back of the net."
The Connacht side are seven points clear of bottom of the table Cork City and four points behind Galway United with nine games to play.
"If we play the way we played tonight we are going to pick up a lot more wins than losses," he added.
"These are special nights when you come up to Dalymount a get a win...we’re delighted we are in the quarter-finals and in the hat for the next round."
Meanwhile, Bohs boss Alan Reynolds (above) was honest in his appraisal, conceding his team, second in the league, got what they deserved.
"I thought we never turned up, I thought we got what we deserved, in fairness," he said.
"Not that we haven't spoken about their threats and the problems they cause. We just never showed up.
"I think we left everyone down as players and staff. I think there's been nights here where you take criticism coming in.
"We deserve everything we get after that because that was poor."
"I don't blame them [the fans for being angry].
"Us as players, we get that.
"Dawson Devoy has been outstanding. In my eyes, the best midfielder in the league this year. And tonight, he has an off night at his standards and nobody else turns up. Nobody else comes over and says, 'you know what, I'll take over and I'll carry it’.
"I spoke to the players about this. We deserve everything you get from that. That performance was really poor."
On Dayle Rooney’s saved penalty (above), he added: "Yeah, but it would have covered over things.
"We could have went on and won it, but, let's be honest, we didn't create enough.
"We didn't defend properly, and we didn't win duels. We didn't do anything that we have done."
"It's just a flat performance and extremely disappointing.
"What we've done all year is we've applied ourselves and we've worked extremely hard.
"Just feeling we left ourselves down, that’s probably the message.
"But we don't get too carried away when we're having a good run. Just nine games to go, let's crack on."
Watch Derry City v Drogheda United in the Sports Direct FAI Cup on Saturday from 7.30pm on RTÉ2 and RTÉ Player
