Millwall got their bid to gatecrash the Premier League back on track by ending in-form Birmingham's unbeaten run with a thumping 3-0 victory.
Goals from Femi Azeez, Tristan Crama and Jake Cooper lifted the Lions back up to third, just four points behind second-placed Middlesbrough.
Birmingham arrived in south London undefeated in nine and with three successive away wins, but they were swept aside at The Den as Millwall bounced back from Saturday's shock home defeat by lowly Portsmouth.
The Blues also had Colombian midfielder Jhon Solis sent off early in the second half on an evening to forget.
Millwall striker Josh Coburn, back in the side after missing out against Pompey through illness, should have opened the scoring after a quarter-of-an-hour only to head Camiel Neghli's cross over the crossbar from six yards.
Birmingham's first opening came when Jay Stansfield tried a curler into the far corner with Lions goalkeeper Anthony Patterson making the save.
But it was the hosts who went ahead in the 25th minute through a peach from Azeez.
Zak Sturge punted the ball forward from halfway and Crama headed it back to the feet of Azeez, who pinged a sweet half-volley beyond James Beadle and into the top corner.
It was a strike Teddy Sheringham, in the stand watching the club where he began his career, would have been proud of.
Sheringham was in the team the last time Millwall were in the top flight, which was two years before the Premier League was formed, but on this evidence they have a genuine chance of getting back among the big boys.
They surged two in front five minutes later when Beadle touched Azeez's 30-yard free-kick onto his left-hand post and Crama snaffled the rebound.
The Lions roared three ahead four minutes after half-time from another Azeez free-kick.
This one was floated deep to Crama, who kept the ball alive on the byline before cutting it back for captain Cooper to sweep home.
Things went from bad to worse for Birmingham when Solis was shown a second yellow card for a bad foul on Casper De Norre.
Millwall could have had more with Macaulay Langstaff heading a good chance just over and Neghli racing through only to clear the crossbar.
The visitors, meanwhile, lost Kai Wagner to a nasty-looking shoulder injury to cap a miserable night for Chris Davies' side, who remain just outside the play-offs.
Millwall's Alex Neil:
"I've watched a lot of Birmingham and player for player they are one of the best teams in the league.
"So we had to be absolutely on it tonight to get a result - and I thought we were. We were excellent. The lads took every instruction and did it brilliantly.
"It's entertaining to watch, high octane going forward, lots of tackles. That's what Millwall at The Den should be.
"I thought we put in one of our best performances. We had a difficult day on Saturday, tonight was an excellent one."
Birmingham's Chris Davies:
"It was a disappointing evening for us. We didn't do enough to get something from the match.
"What we didn't withstand was the direct style of their play; the long balls, free-kicks, throw-ins, we were second best and if you are second best here you are not going to get anything.
"Everything that could have gone wrong went wrong. It was timely reminder of what this league is."
