Sheffield United manager Danny Wilson locked his side in the dressing room for almost an hour and a half after a defensive nightmare led to his side losing 2-0 to Crawley.
Errors by centre-half pairing Neill Collins and Harry Maguire let Crawley in twice in the last 13 minutes as Billy Clarke and Paul Hayes secured victory for the Red Devils at Bramall Lane.
United hit the woodwork through Ryan Flynn's angled drive in the first half and captain Michael Doyle's dipping volley three minutes into the second period as they failed to score for the fourth successive home game.
Wilson said: "There's been a great chat about it, and I think that's what it's been. I don't think it's been a cup-throwing type of conversation because I think we're beyond that at this moment in time.
"We've been done by a couple of mistakes from two boys in particular who have been outstanding for us the last couple of seasons. Unfortunately it cost us in the game but we've had enough chances as well, we've had good chances, hitting the post - we're quite unlucky in that respect.
"Not putting the ball in the back of net has been our problem recently, as you all know. If there's anything to look back on on the night it's that we've had a couple of results that have gone for us as well. So all it does is knock us down by a game."
Sheffield-born Crawley boss Richie Barker hailed the result as the best in his club's history.
Former Blades loanee Clarke struck in the 77th minute after Hayes robbed Collins and squared across goal. Substitute Hayes, on loan from Brentford, sealed the win with a neat finish after dispossessing Maguire with six minutes remaining.
Asked if it was Crawley's ultimate league success, Barker said: "Probably, yeah. Certainly I think the biggest league gate Crawley have ever played in front of, and a fantastic scalp.
"When you look up at the scoreboard and see Sheff United 0, Crawley Town 2, without being disrespectful, sometimes you think it's like a cup result really. We thoroughly deserved it."