But on a quiet night at The Den, the Lions found their roar to condemn Wimbledon to a seventh straight defeat.
Neil Harris set Millwall on their way with his first goal of the season from the spot. The penalty had been awarded after Dons goalkeeper Steve Banks brought down Paul Ifill shortly before halftime. But Wimbledon were furious that referee Paul Durkin allowed play to continue with injured defender Mikele Leigertwood needing treatment inside his own box.
Even so, The Lions should have been at least two goalls ahead by then anyway. Abou Fofana wasted a golden opportunity, blasting wide when hitting the target would have been easier and defender Darren Ward twice went close with two powerful headers.
Fofana should have made it two shortly after the break but blazed the ball over the bar. Harris went close with a snapshot before hitting the crossbar with 70th header and Bob Peeters hit a thunderbolt that skimmed the top of the net from 20 yards out.
The points were secured deep into injury time when Tim Cahill refused to give up a lost ball and found Noel Whelan in the box who netted with a close-range strike deep into stoppage-time.
Millwall Mad Ratings:
Tony Warner 6 - Didn't really have much to do
Kevin Muscat 7 - Came back strong after Saturday's sending off
Robbie Ryan 6 - Linked up well with the midfield
Tim Cahill 8 - A powerhouse performance from the Aussie midfielder
Stuart Nethercott 6 - A so-so performance
Darren Ward 7 - Went close to opening the scoring twice, strong at the back
Dennis Wise 7 - Clearly wanted to put one over his former club
Abou Fofana 7 - Dazzling in parts, ran out of steam in the second half
Bob Peeters 6 - Never gave up but never really got the breaks either
Neil Harris 7 - Opened his account for the season
Paul Ifill 7 - Tore through the Dons defence on more than one occasion
Noel Whelan 7 - Came on to score his third goal of the season