Burton missed the chance to restore their five-point lead in Sky Bet League Two after being held to a 1-1 draw at home to Stevenage.
Midfielder Tom Naylor turned the ball into his own net to give the visitors the lead but Bira Dembele also put through his own goal to level matters on the strok of half-time.
The stalemate ended Burton's run of four successive wins and extended their advantage over Shrewsbury and Wycombe to three points and more significantly 10 points clear of fourth-placed Bury.
Tom Pett wasted an early chance for the visitors but their domination of the opening exchanges was rewarded with Naylor's slip-up in the 12th minute as the on-loan Derby player attempted to clear a Simon Walton header.
Burton defender Shane Cansdell-Sherriff had the ball in the net after 31 minutes only to be ruled offside, but the second own goal of the game put the hosts level seconds before the break, John Mousinho's header bouncing over the line off Dembele.
The pitch continued to deteriorate in teeming rain, with standing water in places, but referee Gary Sutton was happy to allow the game to continue.
Burton began to get on top but a Phil Edwards header came back off a post before Nasser El Khayati skied a 10-yard shot and then fired narrowly wide as the hosts wasted the better of the chances to take all three points.