The delayed 2020/21 campaign got underway on 12th September - but not before the Carabao Cup kicked off the season a week earlier.
Goals from Scott Malone, a Jordan Tunnicliffe own-goal and Matt Smith eased The Lions through to Round Two at Crawley Town, where they were drawn against another Sky Bet League Two side in Cheltenham Town.
The League campaign began with a goalless draw at home to Stoke City, before Ryan Leonard, Connor Mahoney and Smith were all on target as Millwall advanced to Round Three of the Carabao Cup at The Robins' expense.
Jed Wallace scored his first goal of the season as Gary Rowett's side registered a first Championship victory of the campaign at Rotherham United on 19th September, before Premier League outfit Burnley ended The Lions' Carabao Cup hopes at the Third Round stage four nights later.
A London derby draw with Brentford followed, before a first League defeat got October underway courtesy of Swansea City, but from there The Lions went on a run of just one defeat in 10 matches, beginning with a 2-1 success at Adams Park against Wycombe Wanderers - Jed Wallace (pen) and Ryan Leonard finding the back of the net.
Martin Cranie's own-goal and Connor Mahoney's strike ended Luton Town's resistance in a Sky Sports meeting on 20th October, with two goals late in the first-half ensuring The Lions and Barnsley drew 1-1 at The Den four days later.
Just days before the club's next game at Preston North End, however, manager Rowett and numerous members of his coaching staff contracted COVID-19, meaning that senior squad members Alex Pearce and Shaun Williams took charge at Deepdale - and it paid off, as new loan signing Kenneth Zohore and a Jed Wallace penalty-kick gave The Lions an outstanding 2-0 victory.
The good feeling was stopped in its tracks on Halloween, however, as Huddersfield Town were 3-0 winners at The Den, but the month of November was to produce an unbeaten run of its own - five consecutive draws - as points were picked up against Norwich City, Sheffield Wednesday, Cardiff City, Reading and Birmingham City.
Take a look at a selection of imagery from Part One of our 2020/21 season review above.