Although Rovers sit in ninth spot in the table, three places below their hosts, a victory will see them move past the Lions and potentially into the top six.
Match preview
There was a time not so long ago when both of these teams would have felt confident about achieving a top-six finish, but only one of these teams will move through to the playoffs.
Despite winning just two of their last eight matches, Millwall have managed to keep their fate in their own hands, holding a two-point lead over the chasing pack.
Importantly, the second of those wins came last time out as they edged out Blackpool by a 3-2 scoreline, twice repelling comebacks from their homes to prevail by a 75th-minute penalty.
As a result, victory will set up a semi-final showdown with Luton Town or Middlesbrough, yet a draw would let in either Sunderland or West Bromwich Albion to move ahead of them.
Given the small margins of error with regards to goal difference, there is an argument that Gary Rowett's realistically need a win, whereas defeat will hand a lifeline to their opponents.
Even if Blackburn emerge victorious in the capital, they are relying on Sunderland and West Brom failing to win their respective fixtures at Preston North End and Swansea City.
Nevertheless, Jon Dahl Tomasson knows that his side can only focus on their own match and hope for the best, and streamlining their priorities may benefit them after a poor run of form.
Rovers have failed to win any of their last eight fixtures, five of them ending in draws, but a late equaliser against Luton Town last time out has at least given the visitors hope ahead of their visit to London.
While goals have proven to be an issue, Blackburn have not conceded more than once in any of their last five matches, a statistic which deserves respect ahead of a contest of this magnitude.
Millwall Championship form:
D
L
W
L
L
W
Blackburn Rovers Championship form:
D
D
D
D
L
D
Team News
A switch to a back three worked for Millwall last time out, but Rowett must decide whether to make any changes to personnel.
Dan McNamara may return at right wing-back in place of Jamie Shackleton, who deputised there versus Blackpool, but the remainder of the side may stay the same.
Tomasson has revealed that Sam Gallagher should be fit to take his place in the Blackburn squad after a hamstring injury.
Bradley Dack is a doubt after missing a number of training sessions, but he would likely not have started this fixture.
Sorba Thomas could return on the right flank in what may be the only alteration from the team that started the Luton contest.
Millwall possible starting lineup:
Long; Leonard, Hutchinson, Cooper; McNamara, Mitchell, Saville, Styles; Flemming, Bradshaw, Watmore
Blackburn Rovers possible starting lineup:
Pears; Rankin-Costello, Carter, Hyam, Pickering; Travis, A.Wharton; Thomas, Szmodics, Brereton-Diaz; Dolan
We say: Millwall 1-2 Blackburn Rovers
Both teams have been far from impressive of late and that leads us to expect a tense affair to play out at The Den. With the shackles needing to come off with Blackburn, that could benefit them, and we would not be surprised to see Rovers snatch victory in the closing stages.