Sean Dyche urged his side to rediscover their cutting edge after throwing away a golden chance to reach the last 16 of the Carabao Cup.
The Clarets were in control of the third-round tie at Burton after Kevin Long’s towering header gave them a half time lead.
Burnley then saw a handful of chances to seal the game go begging – along with an inspired goalkeeping display from Dimitar Evtimov – before two goals in the final half hour caused an upset.
“We had control of that game, but if you don’t take chances the opposition will at some stage,” said Clarets boss Dyche.
“We certainly created enough, certainly got ourselves in good enough positions and certainly played a lot of good football.
“But, and it’s a very big negative on this occasion, we didn’t take our chances.
“We’ve said it all season and it’s been my biggest bug-bear of the season. I don’t want to by hyper-critical because we’ve probably taken four out of eight really good chances last Saturday.
“Tonight we had better chances, so it’s an annoying one and I am sure you can feel my frustration.
“We are missing that clinical edge, but that is so, so valuable in football.
“We found it on Saturday and we’ll have to find it again. We just didn’t find it tonight.”
Long’s header from Johann Berg Gudmundsson’s corner, five minutes before half time, put Burnley ahead.
With Steven Defour starting his first game since January, and enjoying a good half in the midfield engine room, the omens were good.
And as the second half wore on, and Burnley looked to kill the game off, Evtimov made two good saves from Chris Wood and Gudmundsson, before Ashley Barnes rattled the inside of the post from distance with his first touch as a substitute and Ashley Westwood volleyed just over.
And the visitors were made to pay for their profligacy when Liam Boyce drilled home a deflected shot just after the hour, and Jamie Allen slotted home the winner eight minutes from time.
Dyche added: “If you are in a game like that and miss so many chances, it affects the feel of the game because they sense it could be their night.
“They got a break with a deflection for the first, which sent Tom (Heaton) the wrong way, and the second one is just poor defending; it’s as simple as that.
“What we have to do is stay calm, stay resolute and keep making chances, which we did. Then they get a second and you are thinking ‘how does that happen?’
“But that’s football and that seems to happen most of all in this competition, in the early rounds.
“We can’t put our finger on it, but the one thing I am clear-minded about is that team I put out tonight was good enough to win that game.
“I must give Burton credit because they have stuck to task, rode their luck and scored a couple of goals.
“But we should have taken care of ourselves tonight and that game should have been dead.”