Kevin Nugent was happy enough with his side's performance in Tuesday's 0-0 draw with Swansea City, but also bemoaned a "lack of cutting edge" in the stalemate.
Millwall's Under 23s created numerous chances against The Swans, but ultimately had to settle for a Professional Development League point in South Wales.
Dan Moss, however, did have a goal disallowed for offside.
"We were quite unfortunate - a slight bit of luck was missing, but we needed a bit more cutting edge of quality in the final third, around the box," Nugent told millwallfc.co.uk.
"Equally, you could tell that we hadn't played for around a month in our performance, but the lads also gave everything, so that side of it was quite pleasing."
The bottom-placed Swans held top-of-the-table Millwall, who were coming into the game off the back of a 6-1 demolition of Colchester United, to a goalless draw - and Nugent explained how, despite forcing the issue for most of the game, his players will have to "learn from" the afternoon.
"I said to the lads that people would be expecting us to win the game. They put 10 men behind the ball, but when you get enough chances in the box like we did, you have to put them to bed. We didn't quite do that, though.
"We did enough to win it, but we didn't have the cutting edge - that's something they'll have to learn from."