Millwall's Under 23s were 2-0 winners over Charlton Athletic in the Professional Development League at Princes Park on Monday afternoon.
Reuben Duncan and George Alexander were on target as The Lions gained local bragging rights.
Kevin Nugent opted to field Frank Fielding in goal once again, with the likes of Jay Barton, Nana Boateng, Hayden Muller and Jacob Munting, who all featured in the Under 18s FA Youth Cup victory over Fleetwood Town, filling the bench.
The Lions were largely dominant in the first-half but had nothing to show for their efforts - Junior Tiensia, Duncan and Alexander were just a number of the players who lined up shots against Charlton goalkeeper Ashley Maynard-Brewer, but they were unable to find a way past the stopper.
That was until two minutes into first-half stoppage-time, when Duncan capitalised on a poor free-kick from The Addicks and proceeded to lob Maynard-Brewer from around 40 yards out, hitting the post before the ball rolled into the other side of the net.
The Lions continued their dominance in the second-half as Tiensia, Duncan and Besart Topalloj all had a go at goal, but the lead remained at just one.
With 67 minutes on the clock, however, Alexander showed a poacher's instinct to turn the ball home from close range and double Millwall's lead.
There were further chances from there to extend the scoreline - most notably for Isaac Olaofe - but no more goals were added, with The Lions settling for a two-goal derby victory away from home.
Charlton Athletic: Maynard-Brewer, Yao, Stevenson, Maloney, Keefe, French, Vennings, Morgan, Isiaka, Wiredu, Quitrina. Subs: Osaghae, Odoh, Powell, Clayden, Ocran.
Bookings: Morgan, Maloney, Ayo
Millwall: Fielding, Brown, Tiensia, Topalloj, Ransom, Strachan, Duncan, Skeffington, Alexander, Burey (Boateng), Olaofe. Subs not used: Wright, Barton, Muller, Munting.
Scorer: Duncan 45+2', Alexander 67'
Referee: Steve Hughes