Millwall's Under 23s were defeated 1-0 by Queens Park Rangers in the Professional Development League on Friday afternoon.
Manasse Mampala struck a free-kick with 74 minutes on the clock at Dulwich Hamlet's Champion Hill ground to secure all three points for The R's.
Kevin Nugent was able to name Billy Mitchell in his starting X alongside the likes of Ryan Sandford, George Alexander and Hayden Muller, and it was the latter who was called into action with five minutes on the clock as the defender had to deal with the tricky Ody Alfa.
Reuben Duncan, Nana Boateng and Sean O'Brien then all combined to set-up Alexander, but the striker has just strayed offside before pulling the trigger.
Alex Mitchell had to be replaced with 19 minutes on the clock through injury - Ezekiel Miller his replacement - before the next opportunity went the way of QPR, but Mampala's effort was comfortable for Sandford.
The Lions had a penalty shout turned down on the stroke of half-time as Boateng's shot perhaps struck a Rangers hand, whilst at the other end in the second-half, Nathan Carlyle got a free header wrong and glanced well wide.
Alexander, O'Brien, Muller and Tyler Burey all had attempts to register on the scoresheet, but the opening - and only - goal came on 74 minutes as Mampala curled his free-kick into the net from just outside the penalty area.
Sinclair Armstrong had a chance to double The R's lead but shot wide, with The Lions unable to find a way to goal after that, succumbing to defeat.
Next up for Millwall's Under 23s is a trip to Cardiff City on Tuesday 16th February.
Millwall: Sandford, Muller, Tiensia, A. Mitchell (Miller 19'), B. Mitchell (Davis 46'), Topalloj, Duncan, Burey, Alexander, O'Brien (Skeffington 75'), Boateng. Subs not used: Moss, Allen.