Outside of the runaway top two, these sides have produced some of the best form in the last six fixtures, leaving Boro and the Lions in fifth and sixth position respectively.
Match preview
On the back of six wins from seven in the Championship, Middlesbrough would have fancied their chances of defeating a Brighton & Hove Albion side in the FA Cup which had recently failed to overcome Charlton Athletic in the EFL Cup.
However, Boro were blown away by their Premier League opponents, who led from the 29th minute onwards and went on to score five times at the Riverside Stadium.
Both teams have now scored in Boro's last seven fixtures in all competitions, a record which comes with its pros and cons, but Michael Carrick will recognise that his side must start improving in defence if they wish to remain in the playoff spots.
While it should be noted that almost two thirds of the 33 goals which have been conceded in the Championship this season have come on the road, Boro now have just one clean sheet in 11 games.
On a plus note, Chuba Akpom has remained relentless in front of goal, with nine strikes and an assist coming from his most recent 10 appearances in all competitions.
There was a time not so long ago when it appeared that Millwall may quickly drop down the Championship table, enduring a period of just one win from six games.
Since then, Gary Rowett's team have collected seven points from a possible nine, also keeping three clean sheets in succession versus Watford, Bristol City and Rotherham United.
Millwall are now back in the playoff positions while holding a match in hand, and there is now reason once again for Rowett and his squad to be optimistic about lasting the course when it comes to a promotion bid.
The London outfit possess the joint-third best defensive record in the division at a time when they meet the team with the third-best attacking record.
Millwall did bow out of the FA Cup last weekend, however, succumbing to a 2-0 defeat at home to fellow Championship side Sheffield United.
Middlesbrough Championship form:
W
W
L
W
W
W
Middlesbrough form (all competitions):
W
L
W
W
W
L
Millwall Championship form:
W
L
D
W
D
W
Millwall form (all competitions):
L
D
W
D
W
L
Team News
Having made just one change for the heavy defeat to Brighton, Carrick must consider whether to keep faith with the players who had impressed before that setback.
With Darragh Lenihan expected to remain absent with a foot injury, Paddy McNair should stay in the middle of the backline, but Isaiah Jones and Alex Mowatt are among those who are pushing for recalls.
Aston Villa loanee Cameron Archer is likely to be given more time to get up to speed before being considered for a starting role.
Rowett may look to revert back to the Millwall XI which started the 3-0 win over Rotherham United after being left unimpressed with the performance versus Sheffield United.
Shaun Hutchinson is expected to be passed fit despite dealing with a calf issue, but George Saville is only likely to be named among the replacements.
Middlesbrough possible starting lineup:
Steffen; Smith, Fry, Lenihan, Giles; Howson, Hackney; Forss, Akpom, McGree; Crooks
Millwall possible starting lineup:
Bialkowski; McNamara, Hutchinson, Cooper, Wallace; Mitchell, Styles; Honeyman, Flemming, Voglsammer; Bradshaw
We say: Middlesbrough 2-1 Millwall
Given the size of their defeat in the FA Cup, we do not expect Boro to be the same side that had regularly impressed before that defeat. Nevertheless, the home side should still possess that extra bit of quality in the final third to get over the line in front of their own supporters.