Full-time score from The Valley
Second-half goals from Jermaine Easter and Shane Lowry secured three huge points as Millwall earned the bragging rights following this lunchtime derby date with Charlton Athletic.
Easter, signed on loan from Crystal Palace just 48 hours earlier, made a sensational impact scoring with his very first touch after coming on as a 58th-minute sub for Dany N'Guessan.
Defender Lowry doubled The Lions' tally six minutes later with a stunning 30-yard free-kick that left home keeper David Button grasping at thin air to secure victory.
What had started as a big week for Kenny Jackett's side last Sunday against Blackburn has turned into one of the most fruitful too, with three games and as many clean sheets setting up an FA Cup Semi-Final spot and now, of equal importance, a big Championship win.
"The first goal was always going to be crucial taking into account the condition of the pitch," beamed Jackett, "And nice for Jermaine Easter to score with his first touch too.
There was fantastic confidence from Shane Lowry to take the free-kick for our second. It's one thing doing it on the training ground but a different matter in front of a big crowd.
It was a fabulous freekick - he made it count.
This has been a very good week for us overall and the confidence we have gained will help very much over the coming weeks.
We started the morning five points off the bottom and we needed to get going."
And get going they certainly did as Jackett masterminded another tactical masterpiece.
The manager was forced to make two changes to the team that beat Blackburn in midweek with Karleigh Osborne replacing the suspended Mark Beevers and new loan signing Richard Chaplow handed his debut in place of Andy Keogh.
The first-half of this derby proved to be a fairly uneventful affair, despite the attempts of the travelling fans to stir a Lions team facing their third game in six days.
A sticky, heavy pitch was not conducive to free-flowing football, and with neither team really able to get any attacking rhythm going,there was little goalmouth action of note.
Lions keeper David Forde was called into action after three minutes when he saved at the second attempt, after initially spilling a stinger from Bradley Pritchard.
Rob Hulse, who played for Charlton against Millwall whilst on loan earlier this season, produced a smart turn and cross to pick out Liam Trotter shortly after, but the latter's snap shot flashed a couple of yards wide.
Millwall were forced to reshuffle their defensive pack on the quarter hour when Osborne hobbled off clutching his hamstring and was replaced by Adam Smith.
Lowry moved across to partner Danny Shittu in the heart of defence with Smith slotting in at left-back.
A flying save by Forde tipped Callum Harriott's long range drive behind for a corner who seconds before had raced out to clear at the feet of Danny Haynes as the home side temporarily woke from their slumber.
However it was Millwall who created the best chance of the half just before the break when Chris Taylor nodded an N'Guessan cross into the path of Adam Smith, but he drilled agonisingly wide.
The second-half certainly started with Charlton posing more of a threat and it took a fantastic interception by Shittu to avert the danger when Haynes looked to be racing through.
Some trickery by Harriott forced a foul out of Alan Dunne on the edge of the box but to the relief of the Lions camp, Yann Kermorgant's resulting free-kick dropped a whisker wide of the target.
Jackett made his first change on 58 minutes and within eight seconds of Easter entering the fray, the super sub struck the crucial opening goal. Fellow loanee Chaplow slipped a neat ball through to the striker and Easter did the rest, calmly slotting under the body of Button to send the away fans wild.
You could sense the relief in the team and with the confidence flooding back, Millwall sensed that this game was theirs for the taking.
None more so than Lowry who took a 10 yard run up before hitting an unstoppable 30-yard freekick that gave Button no chance.
Charlton tried desperately to work their way back into the game and did create one half-chance in the 80th-minute when Chris Solly's low centre was saved by Forde, but there was little else for the home fans to get excited about as their team simply ran out of ideas and The Lions comfortably saw out the remainder of the match to secure a thoroughly deserved win.