Both teams have exceeded expectations this season, each sitting eighth in their respective divisions after surprisingly strong campaigns to this point.
The London side are unbeaten in six and have lost just two in their last 17 across all competitions since the former Birmingham City, Derby County and Stoke City boss took over.
Their last outing, a 2-0 victory over Reading, was their fourth win in five games - a run in which they have conceded only once.
Millwall find themselves eighth in the league and just two points off the playoff places as they look to mount an unexpected promotion charge this term.
However, they come up against a Sheffield United side that have impressed greatly since their promotion to the Premier League last season.
The Blades are eighth in the table and have lost just seven times this campaign - the sixth-best record in the division.
However, four of those seven defeats have come against champions-elect Liverpool and reigning champions Manchester City, losing 1-0 at home and 2-0 away against both.
Their defensive record of 23 goals conceded in 24 games is the second-best in the Premier League, behind only Liverpool, who have shipped just 14 in 22 league outings.
Millwall Championship form: LDWWDW
Millwall form (all competitions): DWWWDW
Sheffield United Premier League form: DLLWDL
Sheffield United form (all competitions): LLWWDL
Millwall manager Rowett is likely to be without a trio of players ahead of the visit of the Blades.
Sheffield United head coach Chris Wilder is set to be without just one man for the trip to London.
Striker David McGoldrick will undergo a late fitness test, but may not be risked against Millwall.
Millwall possible starting lineup:
Bialkowski; Romeo, Hutchinson, Cooper, M. Wallace; J. Wallace, Woods, Molumby, Ferguson; Bradshaw, Smith
Sheffield United possible starting lineup:
Verrips; Bryan, Jagielka, Rodwell; Osborn, L. Freeman, Besic, Morrison, K. Freeman; Clarke, Robinson
We say: Millwall 0-2 Sheffield United
Both teams are having excellent seasons, but Sheffield United have been so efficient and solid at the back that it is hard to look past a Blades win against Championship opposition.