AFC Wimbledon turned in what Andy Barcham called "one of the worst performances" of the season as they lost at home to Southend United on Saturday.
Dons failed to register a single shot on target in the entire 90 minutes, as Phil Brown celebrated his fourth anniversary in charge of the Shrimpers with a win.
Wimbledon boss Neal Ardley was "embarrassed" by the display, and Barcham echoed his manager's sentiments.
He said: "That's not what we expected, that's not how we've been performing.
"I don't think we're going to make excuses, no [it's not after the Lord Mayor's Show, after the MK Dons win]. We approach every game the same, prepare the same, the gaffer has said in there that it wasn't good enough, we know that.
"You're going to lose games, but it was how we lost it, things we're usually good at we weren't. We just put in a bad performance. All over the pitch it wasn't good enough."
Wimbledon host a Rochdale side looking to move to within three points of the League One play-off places on Tuesday night.
And Barcham and his team-mates know they must do better.
He added: "We don't have to wait too long to put it right, we'll work out where it went wrong and what we can do better.
"Every game's important [being mid-table is not a problem]. We know it's going to be a tough game and we'll definitely come up with a better performance than this one."
