Joint-manager Stuart Delmonte said: "This win was all about character. It was an even game against a good side, but the players came through again.
"We had to hold our nerve and stay in the game. But we showed our quality when it mattered.
"There are a few match-winners who are helping us at the moment. But I would like to pay tribute to our defence. The back five, whoever has played, have been superb all season and their contribution should not be overlooked."
Adam Tauber’s header had hauled AFC Flixton level before the visitors regained the lead just after the restart.
But Leeker’s brace and Warwick lung-busting run and cool finish condemned Duffys to a rare defeat.
Delmonte added: "We are taking it one game at a time rather than looking ahead.
"We still have four key players who are currently out injured.
"But Dan Garmen, Dan Aylon, Mark Bell and Adam Wilson are all due to return so that bodes well for us. It will only add competition for places."
Report by Darren Witcoop