Wimbledon's surge up the Nationwide Division One table was halted in controversial fashion as Derby came from behind to take the points.
Neil Shipperley gave Wimbledon the lead with his 13th goal of the season before Derby equalised with a goal that looked offside.
Wimbledon also claimed they should have been awarded a penalty when David Connolly was caught by Rams keeper Lee Grant on the half hour when the scores were level.
Wimbledon boss Stuart Murdoch made no excuses for his team's defending and he admitted: Â“We conceded goals too freely and itÂ’s something that needs to be addressed by myself and the players.Â” Derby manager John Gregory was also less than impressed with the performance of his defence and Connolly should have scored at least once in the first half.
The striker struck a post with the goal gaping in the 29th minute and was also denied by Grant in the second half when Shipperely sent him clear.
Deon Burton looped a header over goalkeeper Kelvin Davis in the 48th minute and, after Grant had denied Connolly, substitute Lee Morris held off three defenders to beat Davis with a low shot ten minutes from the end.
Connolly did find the net when he was left unmarked in the 88th minute but by then it was to late for Wimbledon to preserve their unbeaten run.
Derby's celebrations were soured by the news that Italian striker Fabrizio Ravanelli will be out for a further three months following an operation on his left Achilles tendon in Rome on Monday