The Lions are currently on their longest unbeaten run for more than a year, with unexpected victories away to Nottingham Forest and Wigan Athletic being highlights of their four-match streak so far.
Charlton Athletic do still have a game in hand over their London rivals, but with four teams now within three points of the relegation zone, Millwall could well climb out of the bottom three by the end of Easter weekend.
Goal difference could be an issue for the Lions, but they are slowly but surely improving their league-worst tally and it is no longer significantly worse than the teams around them in the table.
Oddly enough, the Lions have fared better against high-flying opposition in recent weeks, particularly away from home. They have won three of their last five matches on the road, all against teams in the top half, having only won one of their previous 18 away games this season.
Middlesbrough, meanwhile, are on a fine run of form themselves and made it four wins on the trot with a surprise 1-0 victory over Burnley at Turf Moor last Saturday.
They have now lost just one of their last nine games, a run that comes too late for a playoff challenge but has seen them rise into the top half of the table.
Boro have not won five league games in a row since 2012, and Aitor Karanka will very much be eyeing that target this weekend as he looks to finish the campaign strongly with a view to pushing for the top six next season.
Their form at the Riverside has been impressive this season, with just three defeats in the league and only one in their last 11. They have been strong defensively in those last 11 too, keeping eight clean sheets.
Possible starting lineups
Middlesbrough: Konstantopoulos; Varga, Woodgate, Omeruo, Friend; Chalobah, Butterfield; Adomah, Tomlin, Williams; Graham
Millwall: Forde; Edwards, Beevers, Dunne, Malone; Woolford, Williams, Bailey, Garvan, Martin; Morison
Sports Mole says: 2-2