The visitors hold a seven-point and seven-place advantage over their hosts on the league front, despite their contrasting results during the latest batch of fixtures in midweek.
After a run of 11 points from 15 matches in the Championship, Gary Rowett will be relieved that the Millwall hierarchy have kept faith in his ability to turn things around at The Den.
However, improving that return with a 1-0 victory away at Huddersfield Town in midweek could be the turning point for the Lions, whose immediate focus will be on moving into the mid-table positions.
Now sitting nine points above the relegation zone, participating in the FA Cup is a welcome distraction for Rowett and his squad, but there will be a desire to make further progress in this competition.
Rowett will want to see more of a ruthless streak from a team which has struggled in the final third all season, but that result has seemingly acted as the catalyst for better performances in the second tier.
Millwall can also head into this contest with a victory over Bristol City still fresh in the memory after winning 2-0 at Ashton Gate on December 15.
That result came in the middle of a three-game losing streak for the Robins, although Dean Holden's team deserve credit for their response since the start of the Christmas and New Year period.
Three wins from five matches have been recorded in all competitions, including a hard-fought triumph over League One Portsmouth in this competition.
While succumbing to Championship leaders Norwich City in midweek came as a blow, Bristol City remain just six points adrift of the playoffs with a game in hand.
Famara Diedhiou has netted three times in five appearances, but the forward requires assistance from his teammates, who continue to be inconsistent in the final third.
Millwall FA Cup form: W
Millwall form (all competitions): DLWDLW
Bristol City FA Cup form: W
Bristol City form (all competitions): LWLWWL
With Watford to come on Tuesday evening, Millwall boss Rowett may be prepared to make sweeping alterations to his side.
Millwall possible starting lineup:
Fielding; Leonard, Pearce, Cooper; Romeo, Woods, Williams, Malone; Bennett, Zohore, Bradshaw
Bristol City possible starting lineup:
Bentley; Mariappa, Moore, Mawson, Rowe; Semenyo, Bakinson, Nagy, Palmer; Bell, Wells
We say: Millwall 2-1 Bristol City
While both clubs will be focused on league matters, the prize money and television revenue on offer means that another win in this competition would be beneficial. We expect a hard-fought affair which will be decided in extra time, leading us to give the edge to the home side.