Thomas Waddingham was the Pompey hero with a late winner to fire them into the play-off positions - for now.
Introduced off the bench following his latest injury comeback, the Australian netted an 82nd-minute winner after Jake Cooper’s clearance deflected off him.
Earlier the Blues came back from 1-0 down after Nicolas Schmid’s awful kick presented Jenson Metcalfe with a sixth-minute lead.
That was cancelled out by Lyndon Dykes’ own goal following an Adrian Segecic free-kick - and then Waddingham claimed a 2-1 success to move the Blues into eighth.
And here are our Pompey player ratings...
1. Goal, Portsmouth forward Thomas Waddingham (20) scores during the EFL Championship match between Portsmouth and Millwall at Fratton Park Stadium, Portsmouth, England on 24th October 2026
Thomas Waddingham celebrates scoring Pompey's winner against Millwall. Picture: Jason Brown | Jason Brown
2. Nicolas Schmid - 5
Awful mistake for opening goal, when he kicked the ball straight to Metcalfe, who scored. Settled down after that, putting the error behind him, but it remained a shocking howler. | Jason Brown
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3. Terry Devlin - 7
Deservedly kept his place following that stunning late equaliser at Wolves and looked the Terry Devlin of last season, with a strong display at right-back. Rock solid defensively and brilliant energy. | Jason Brown
4. Madiodio Dia - 8
Another whole-hearted defensive showing from a player rapidly growing into a Fratton faithful. One brilliant block with his head while grounded in the penalty area in the second half summed him up perfectly. | Jason Brown