Crawley manager Richie Barker hailed Tuesday's 2-0 win at Sheffield United in League One as the best result in the club's history.
Former Blades loanee Billy Clarke tapped in the 77th-minute opener and substitute Paul Hayes sealed the surprise victory with a neat finish with six minutes remaining at Bramall Lane.
Asked if it was Crawley's ultimate league success, Sheffield-born Barker said: "Probably, yeah. Certainly I think the biggest league crowd Crawley have ever played in front of, and a fantastic scalp.
"When you look up at the scoreboard and see Sheffield United 0, Crawley Town 2, without being disrespectful, sometimes you think it's like a cup result really. We thoroughly deserved it.
"We worked on something on Monday, I won't tell you what it is because I don't want people to know, and to be fair the players were fantastic in terms of taking it on board.
"In terms of executing a game plan they took all the information on board and then after that we passed it extremely well."