Head coach Geordan Murphy blamed self-inflicted wounds as Leicester Tigers’ European campaign ended on a losing note against Ulster on Saturday.
Tigers led 13-0 early in the second half but then conceded two converted tries in a five-minute period of intense pressure as Ulster took full advantage to secure a win which guaranteed their place in the quarter-finals.
“I’m devastated because I thought the game was ours,” said Murphy.
“At 13-up I thought the game was in our control. It was working well for us and we felt in control, but then all of a sudden we started making mistakes.”
A big physical effort up front, combined with a smartly taken try by Matt Toomua, had given Tigers the start they were looking for, before the visitors played their way back into the game.
“I thought the forwards worked really hard – there is blood on the floor in the dressing room and a lot of tried bodies – but we have to be smarter,” added Murphy.
“We got into their 22 three or four times in the first half and probably got a sight of their line a couple of times in the second half but were very loose and we turned over ball far too many times.
“You cannot visit their goal zone without scoring points.
“Everyone is working hard for each other, there is endeavour there, but there are a few execution issues.”
Ulster finished second in the pool behind Racing 92 but qualified for the last eight as the best runners-up and will travel to defending champions Leinster.
Quarter-Finals: Saracens v Glasgow Warriors, Edinburgh Rugby v Munster Rugby, Leinster Rugby v Ulster Rugby, Racing 92 v Toulouse
Semi-Final draw: Saracens / Glasgow Warriors v Edinburgh Rugby v Munster Rugby, Leinster Rugby / Ulster Rugby v Racing 92 v Toulouse