NEIL Harris revealed he was critical of his players after their 2-0 defeat to Scunthorpe in midweek – but praised them for their response in a thumping 3-0 win over Peterborough on Saturday afternoon.
Steve Morison fired home a brace either side of Lee Gregory's 20th goal of the season to lift the Lions to fifth place in the table.
Millwall survived an early scare when Mark Beevers, back in the side in place of Sid Nelson, half-volleyed a back-pass from 40 yards that Jordan Archer had to spectacularly head over the bar.
Morison put Millwall ahead after half an hour when he headed home Gregory's cross to the back post.
Gregory had missed a chance to put Millwall in front earlier when he blazed over from two yards, but he made up for it four minutes into the second half when he nodded Beevers' header from Shane Ferguson's free-kick past Ben Alnwick.
Morison got his 12th of the season when he powered Ferguson's corner past Alnwich just after the hour mark and he was given a standing ovation by the home fans when he came off in the 73rd minute for John Marquis.
Millwall started with Ben Thompson in midfield in place of the suspended Shaun Williams and Mahlon Romeo made his fourth consecutive start at right-back.
Harris also named five players who have come through the club's youth system on the bench, and he was thrilled with the reaction of his squad to the defeat by the Iron.
"I think it was a good statement of intent from us that we bounced back from Tuesday night's below-par performance against a very well-organised Scunthorpe side," Harris said.
"We weren't quite right. So we did a lot of work on Thursday and Friday and a lot of credit goes to the players because they had some criticism on Tuesday night from all angles, including from me.
"But they've dealt with it in the right manner, and we've learnt as a group. I told them we have to learn from the negatives as well as the positives.
"On Thursday, certainly from the video analysis of the game, we've done that. And on Friday their attitude to train and to learn about putting a game plan into execution was evident today and probably well above some of their years of age."