Kevin Lisbie struck in the final minute to secure a dramatic sixth straight home win for Millwall.
The striker, on as a substitute, touched in a cross from James Henry for only his second goal of the season to finally see off a dogged Doncaster side 1-0.
Millwall created the majority of the chances at The Den but they were without their 13-goal top scorer Steve Morison through injury, and for 89 minutes it showed.
Wales international Morison, who was linked with Fulham and Wolves last month, gave the club a boost before kick-off by signing a new contract.
But there was precious little else to cheer in south London until Lisbie's late intervention.
The hosts, who are pushing for a place in the play-offs, could have opened the scoring in the eighth minute but skipper Alan Dunne's header flew over.
Five minutes later Henry's header was too close to Rovers goalkeeper Gary Woods, before the winger blasted a long-range effort wide.
Craig Eastmond, on loan at The Den from Arsenal, then teed up Liam Trotter but the midfielder planted his header over the top.
Trotter thought he had put Millwall into the lead in the 39th minute when his downward header from Henry's free-kick hit the back of the net, but his celebration was cut short by the linesman's offside flag.
After the break Dunne sent Theo Robinson scampering through but his angled shot was easily dealt with by Woods.
Trotter passed up another opportunity on the hour mark when he headed a corner from Scott Barron wide, before another long-range Henry effort flew the wrong side of the post.
Rovers did show some attacking intent as the second half progressed and, after Millwall only half-cleared a free-kick from Brian Stock, David Forde was forced to pull off a fine save from Sam Hird's shot.
Ryan Mason fired wide and Steve Brooker sent his shot too high as Rovers sensed the possibility of a surprise victory against a Millwall side beaten by the last kick of the game at Norwich in midweek.
But this time it was the Lions who were celebrating courtesy of Lisbie, who came on as a substitute in the 58th minute.
The former Charlton striker got the slightest of touches from Henry's cross at the death to secure yet another home win for the Lions.
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