Boro were unable to make it three wins in the space of seven days after going down to an own goal at Millwall.
Neil Warnock’s side dominated the second half of the contest but paid the price for conceding a sloppy goal during the opening period.
It wasn’t a pretty start and It took almost half an hour for the first real opportunity when Marcus Bettinelli pulled off a great save to deny Jed Wallace after the Millwall man was released on goal.
Moments later, Wallace escaped again, this time down the left flank after Djed Spence had been caught in possession, and his low cross was turned into the net by the unfortunate Grant Hall. It was to prove the decisive moment in the game.
The home side had another good opportunity before the break when they moved forward quickly again, and Danny McNamara fluffed the chance to double Millwall’s lead when he fired wide of the mark.
Boro’s response came when Marvin Johnson showed good feet to supply Yannick Bolasie, but his effort squirmed just wide of the mark.
And Boro were dealt another blow before half-time when the industrious Marcus Tavernier was forced out of the action with injury, giving George Saville the opportunity against his former club.
That was the first of four changes in a matter of minutes with Nathaniel Mendez-Laing, Duncan Watmore, and Ashley Fletcher all coming in at half-time.
That proved the cue for Warnock’s side to start firmly on the front foot. Set-piece deliveries from Paddy McNair and Jonny Howson caused problems at the back for Millwall and after good work by Mendez-Laing, Saville was denied by the legs of Bartosz Bialkowski.
A Johnson ball in to the box caused panic and Watmore had a shot deflected wide and the home side were on the rack as Boro showed real purpose and intent.
To their credit, the home side threw themselves in front of every ball and made some vital blocks to maintain their lead.
When Boro did beat the blocks, Bialkowski was on hand to make another superb reaction save to deny McNair.
As the clock ticked down, Boro were so committed to salvaging something and making the dominance count that Millwall almost profited from a quick break but sub Jon Dadi Bodvarsson saw a chance tipped over the bar by Bettinelli.
But for all Boro knocked, Millwall held firm to pick up the points leaving Warnock’s side knowing they have it all do to secure a top six finish with just eight games remaining.