Phil Brown accused his players of producing the `worst performance` of his reign as Preston manager in a 4-0 defeat at Millwall.
Darren Purse, Josh McQuoid, John Marquis and James Henry gave the Lions a huge boost in their late surge for a play-off place, but the Lilywhites are now five points from safety with only three games remaining.
Brown said: "If we play like that again then we will be going down. But you won't be getting that repeat performance I can assure you.
"I can't answer why we got that display. That is the worst performance I have seen in my time in charge and it was completely unacceptable.
"We prepared well, we trained well, but when we got here we got outmuscled, outbattled and outplayed.
"You know what you're going to get when you come here and we just didn't stand up to it."