Gareth Ainsworth says his side were “unrecognisable” during their defeat at York City on Saturday.
A poor first-half showing saw Wanderers go into the break 2-0 down, and despite an improved display after the restart they were unable to get back into the contest.
He said: “The second goal was one I still can’t believe we conceded, it came from our own corner. It’s compounded everything and left us with a mountain to climb.
“It’s a sloppy goal to concede and I'm very unhappy with the number of times they countered on our own corners. There were some unrecognisable players out there, hopefully it was a one-off.
“I apologise to the fans who made the journey, because that wasn’t up to standard for me.
“The onslaught we took in the first five minutes of the game finally told with them getting the penalty. I wasn’t happy with the way we started the game, second half we battled hard and managed to keep it 0-0 but we should have done that in the first half.
“I had a lot of unrecognisable players today. They weren’t at the standards I have set and the standards they have set, and they’ll be disappointed with the performance.
“They won’t be getting off with that one lightly – I’ll be telling people just what I think of where they went wrong.”
Chairboys have the chance to right those wrongs on Tuesday when they visit Cheltenham Town (k.o 7.45pm).
Ainsworth added: “There are players that will know that they need to produce a performance week-in, week-out for us to get to safety.
“There will probably be a few changes on Tuesday, and there will definitely be one with Sam Togwell being sent-off.
“Stu Lewis trained on Thursday and was ready to come, but he came in on Friday with an illness and the doctor sent him home.
“That was a blow as Stu is a big performer for us and I’m sure he will be back soon.”