Facts and figures ahead of this weekend's big game
Last season Neil Harris' charges finished victorious both home and away, securing a 3-1 win at The Den followed by a 1-0 success at Spotland courtesy of Lee Gregory's 54th-minute winner.
Those two matches were the first time that the sides had locked horns since the Fourth Division days of April 1965, when they played each other twice in the space of five days.
The first game at The Den on 16th April finished 0-0 and the return, a 2-0 success for The Lions, thanks to goals from Hugh Curran (pen) and Dennis John.
You have to go back a further four years to 1961 to revisit Rochdale's last win against Millwall. On that occasion Dale claimed a 4-1 victory in what would be the most successful season of the northerner's history, as they went on to become the first club from the bottom division to reach the League Cup Final - where they lost to Norwich City.