Millwall's Under 23s won the battle of South London on Monday afternoon as they defeated Crystal Palace 1-0 in the Professional Development League.
The match, played at The Eagles' Copers Cope training ground, was settled by David Ajiboye's second-half strike.
The young Lions started the derby the better, with Mason Saunders-Henry, Isaac Olaofe and Noel Leighton forcing Palace goalkeeper Joe Tupper into a trio of saves.
The second-half started in the same vain, with Millwall taking the lead on 53 minutes. A Palace corner-kick was thwarted by Harry Girling, who set Ajiboye away with a long throw. The Brighton and Hove Albion loanee then evaded the challenge of Tyler Brown before slotting beyond Tupper to score the only goal of the game.
The Eagles attempted to get back on level terms as the minutes ticked away, but the late sending off of Sam Woods ended any hopes as Millwall secured a priceless victory.
Next up for Kevin Nugent's side is the trip to Queens Park Rangers on Monday afternoon.
Millwall: Girling, McNamara, Tiensia, Donovan, Debrah, Mbulu, Ajiboye (Sinclair 75'), Hanson, Leighton, Olaofe (Brymora 85'), Saunders-Henry. Subs not used: Wicks, Wright, Neary.