Kevin Nugent bemoaned a "flat" performance in Friday afternoon's 1-0 Professional Development League defeat to Queens Park Rangers - and stated that too many of his squad "wanted to play their own game" after going a goal down at Champion Hill.
Manasse Mamapala struck the winner in the 74th minute at the home of Dulwich Hamlet, leaving the Under 23s without a win in four minutes.
"Overall, it was quite a flat performance," the manager told millwallfc.co.uk. "We didn't play very well and there wasn't any fantastic individual performances.
"For the majority of the game, we were quite steady. I always thought the game was going to be 1-0. I thought we had to limit their opportunities by being trustworthy and not giving away free-kicks and set-pieces so they could put the ball in the box - that's what they scored from.
"All the players weren't fully at it, but we were hoping to be the team that would force a mistake at the other end or hoping there would be a little bit of individual creativity, which we have the personnel to do.
"However, what I was disappointed about was that after they scored, we had too many players who wanted to go ahead and play their own game, and were moaning at others. That isn't what we are about."
Alex Mitchell had to withdraw from the game in just the 19th minute, and Nugent explained how that substitution meant an alteration in thinking - on top of changes made from Monday's draw away to Charlton Athletic.
"It did [change our game plan] a bit. We've had a few players who have picked up niggles from Monday's game, so we've had to leave them out. Alex has picked up one as well now, unfortunately, so we've got to be a bit careful with them."