Millwall's Under 23s were defeated 3-0 by Cardiff City in the Professional Development League on Tuesday afternoon.
The Lions were reduced to 10 men on the stroke of half-time after George Alexander was shown a straight red card for an unknown incident.
Chances were few and far between in the opening stages of the game, with Alexander the only man to try his luck for Millwall, striking wide from a pass forward.
In the 12th minute, however, Cardiff took the lead through Keenan Patten's thumping effort from the edge of the penalty area, before Kieron Evans doubled The Bluebirds' advantage with a smart finish from inside the box.
Dan Moss nodded Sean O'Brien's free-kick wide as Kevin Nugent's side looked to get back into proceedings, but Jordan Gillmore was the busier of the goalkeepers, having to push an effort on to the post shortly before the 45-minute mark.
In first-half stoppage-time came the big talking point, however, as Alexander was given his marching orders by the referee.
Nana Boateng poked an effort wide of the post as The Lions tried to muster a comeback in the second-half, but with the rain tumbling down in South Wales and the 10 men tiring, Cardiff added a third through Ntazana Mayembe late on.
Next up for Millwall's Under 23s is an away game at Watford on Monday 22nd February.
Millwall: Gillmore, Miller, Okoli, Skeffington, Moss, Topalloj, Davis, Duncan, Alexander, O'Brien, Boateng. Subs: Bate, Hammon, Allen, Abdulmalik.
Sent Off: Alexander