Harris upbeat despite Leicester lossCaretaker boss Neil Harris said The Lions could take plenty of positives from their New Year's Day game with Leicester, despite slipping to a 3-1 defeat against Nigel Pearson's League leaders.
Anthony Knockaert's 20-yard strike saw The Foxes into the interval a goal to the good before David Nugent headed home to double the away side's advantage less than three minutes into the second-half.
Richard Chaplow scored his first Millwall goal to reduce the deficit with just over 20 minutes to go, but with Millwall pushing for an equaliser, Jeff Schlupp slotted under David Forde on the counter attack to secure all three points.
"I'm gutted for the boys because they were fantastic today," Harris said. "Scott and I asked for tempo and desire ahead of the game and that was exactly what we got.
"For the majority of the match we were the better side and our only disappointment was that the final ball was perhaps lacking a little bit.
"When we pulled it back to 2-1 we took Jimmy (Abdou) off and went for it, and Jermaine (Easter), four times out of five, finishes the one-on-one chance he had."
Next up for The Lions is the FA Cup Third Round tie at Southend United on Saturday, and Chopper is excited at the prospect of coming up against his former side.
"It's a great game for the fans, a local one, and they will be there to get behind the players.
"I want passion from them, just like what we've seen up at Doncaster and again against Leicester.
"We'll come in tomorrow (Thursday), regroup, and go again for a tricky but winnable Cup tie. There's plenty of positives for us to take there from today's game."