The fans were back at The Den but Millwall's winless run in the Championship was extended to eight games.
Story of the game
Jed Wallace had the first chance of the game on 12 minutes. He charged through midfield and best two Derby County defenders and bared down on goal but David Marshall denied him.
Derby had some early chances themselves Kamil Jozwiak sending an early shot wide before former Charlton Athletic defender Krystian Bielik headed over on 17 minutes.
Graeme Shinnie went close for Derby on 56 minutes but his effort from 25 yards did not challenge Lions stopper keeper Bartosz Bialkowski.
Troy Parrott was introduced in the 57th minute. His first action was a shot from the edge of the box that was held well by Marshall.
Shane Ferguson fired a free-kick into the wall just a couple of minutes before.
Derby took the lead on the 70th minute. Jason Knight smashing the ball home after Bialkowski had made the save from Martyn Waghorn.
The fan return
It's been nine long months since Millwall fans had been inside The Den to cheer on their team and it was a very special moment when the players came out at the start of the match. The fans and players were reunited together you could tell they were very happy to be back and the players were just as happy to welcome them back.
A tight and cagey game
This was a game between two sides who are both struggling for form. Millwall came into the game winless in eight and with five draws in their last six games, while Derby were bottom of the league and winless in twelve.
It showed at periods with both sides nervous to make a mistake that could just let the other side in. There was, of course, more pressure on the home side with the return of the fans inside The Den.
Gary Rowett made five changes to the Millwall side, Jake Cooper, Shane Ferguson, Ben Thompson, Matt Smith and Ryan Leonard all came into the side.
Derby named former Charlton centre-back Krystian Bielik in their starting eleven.