Walsall moved back to within three points of League One's automatic promotion places on Tuesday with a 2-1 victory over struggling Shrewsbury Town.
A 4-0 defeat to Bradford City on Saturday had enabled Millwall to climb above Jonathan Whitney's side, but Walsall bounced back with a comfortable win in their game in hand.
First-half goals from Kieron Morris and Rico Henry sealed all three points to give Walsall hope of a top-two finish with two games to go.
In the Championship, Hull City made it five games unbeaten as mid-table Brentford were brushed aside 2-0.
A Harlee Dean own goal had given Steve Bruce's side the lead just after the half-hour mark and Mohamed Diame doubled their advantage on the brink of half-time – albeit after Adama Diomande had missed a penalty for the hosts.
Meanwhile, Portsmouth secured their play-off place in League Two thanks to a 1-0 triumph over AFC Wimbledon.
Michael Smith struck the decisive goal as the 2008 FA Cup winners moved nine points clear of eighth-placed Cambridge United with two to play, but Wimbledon still need a win to guarantee their spot.
Get the best features, fun and footballing frolics straight to your inbox every week.
Thank you for signing up to Four Four Two. You will receive a verification email shortly.
There was a problem. Please refresh the page and try again.