The Dane said he remained calm in the dressing room after seeing his side squander a 2-0 half-time lead to concede four goals in an incredible second-half collapse.

"Preston thoroughly deserved the win. We scored two good goals, but there were too many crosses and we allowed too many things around our box, so we knew we had to step up," he said.

"In the second half it was back to the horror show of my time when I came here and goals were flying in left, right and centre, so I am 100 per cent that this is going to be a one off."

Frank blamed poor reactions to situations around the pitch for the collapse, which saw his normally reliable defence ship three goals in 11 minutes.

He said: "We weren't complacent. I didn't see a team that wasn't working hard, but all the goals were avoidable and that's why I'm calm because we will get it right. Sometimes things happen that you just can't explain.

"Their goals came out of nowhere when we were so good defensively up to half-time. We will sit down and look at the video, but sometimes it is the smaller details that can cost you."

Brentford's cause was hampered early on when they lost Christian Norgaard with an ankle injury that will keep him out of the Denmark squad for their upcoming National League games.

"I can't say that if he'd stayed on the pitch we'd have won, but if you want to win matches you need to learn to do it without one of your best players once in a while," said Frank.

Delighted Preston boss Alex Neil was full of praise for his side's comeback.

"It was strange because we played well in the first half but switched off with two transitions. The second goal we have to give them credit, and at that point it's difficult," he said.

But a half-time team talk where he urged his players to be positive reaped rewards.

Neil added: "We had to get the next goal and that's dangerous against Brentford because they can hit you.

"We needed to get after them and lock them in. We did that after the break, won our individual battles and, when we went forward, we went forward with more belief."

He blamed a lack of conviction for the first-half display, adding: "I don't think we felt we could get a goal, but when we got the first it gave us belief and urgency in the way we played.

"The performance wasn't that bad in the first half. There were just things we needed to brush up on. We needed to do things better and we did and we showed good bravery in the second half.

"We won the second balls in the second half and they couldn't find a solution. I didn't need them to repair anything, just do it better."

"It's the first time we've been here and had more possession than Brentford. We never lack character and today we showed that bit of quality you need to score four away from home."