Millwall continued their march towards the npower Championship play-offs as goals from James Henry, Liam Trotter and Steve Morison sank Leeds 3-2.
Henry blasted the Lions into the lead with a spectacular free-kick and Trotter doubled the advantage with a tap-in before the interval at a raucous, sold-out Den.
Luciano Becchio pulled one back for Leeds early in the second half, but Wales striker Morison made the points safe before Andy O'Brien scored with the last kick of the match.
These two sides have become big rivals in recent years, having both made heavy weather of getting out of League One until they were eventually promoted last season.
They could be on course to meet in the play-offs again with Leeds' hopes of automatic promotion fading fast.