MILLWALL must beat Middlesbrough on Saturday and hope Derby lose at Aston Villa to move back into the top six with a game to go in the Championship this season.
Derby's 3-1 win over Cardiff on Tuesday night saw them leapfrog Millwall into sixth. The Rams have a plus-seven superior goal difference.
If Derby get a result at Villa, Millwall would need to defeat Boro by five goals to go into sixth.
The Lions can still take it to the final day against Aston Villa even if they lose, provided Derby also lose at Villa Park.
However, defeat at The Riverside Stadium and a Derby draw would effectively end Millwall's play-off chances given that goal difference.
Brentford, Preston, Bristol City and Sheffield United are also all still in the top-six race.
Image: Millwall FC