Che Adams' 13th goal of the seasson wasn't enough to prevent Blues suffering a narrow defeat against Boro.BCFC
Lewis Wing fired Boro into the lead late in the first-half, before Che Adams levelled the scores with his 13th goal of the season after 79 minutes.
But with Blues pushing on to try and claim all three points they were hit on the counter-attack by a goal from Boro sub Britt Assombalonga.
Blues struggled to pose any real attacking threat in the first 45 minutes of the contest but put in a much improved showing after the break and were unlucky not to come away with at least a point against promotion-chasing Boro.
There were two changes to the Blues side that lost in the FA Cup to West Ham last weekend, with Jota and Kristian Pedersen returning to the starting XI in place Connor Mahoney and Wes Harding.
Isaac Vassell was in the matchday squad for the first time in almost 15 months; albeit on the substitutes’ bench.
It was a scrappy opening from both sides, but it was the visitors that arguably had the edge with Blues struggling to string passes together or keep hold of the ball.
So it was no surprise when the first two openings of the game dropped to Boro's Jordan Hugill.
His first was a close-range effort which was blocked and the second a volleyed chance from the edge of the box which flew well wide.
It took until the 21st minute for Blues' first sight on goal when Lukas Jutkiewicz was brought down on the edge of the Boro box for a free-kick.
Jota stepped up but was unable to keep the ball down and it curled just over Darren Randolph's bar.
Boro came desperately close to taking the lead just after the half-hour mark and would have done so but for two brilliant blocks by Pedersen.
First Pedersen denied Hugill and then the rebound was fired in by Fry, and the Dane was there again to deny him.
But Boro were not to be denied for much longer as they took a 37th minute lead after the ball was crossed in from the right and Wing was able to find himself in space at the far post and side-foot the ball into an empty net.
Half-time: Blues 0 Middlesbrough 1
Blues made a solitary change at the break with Craig Gardner replacing his brother Gary in the centre of midfield.
Blues had a massive shout for a penalty when Che Adams burst through into the box and went over.
But instead of pointing to the spot, referee Graham Scott blew for a foul for the visitors and booked the Blues striker for an alleged dive.
That decision inflamed the Blues faithful who began to raise the decibel levels.
And they were almost rewarded with an equaliser just after the hour-mark when Jota fired in a deep free-kick and Harlee Dean headed the ball against the post.
Blues were continuing to up the attacking ante and Jutkiewicz saw his header comfortably saved by Randolph.
Blues then won a free-kick in a terrific position right on the edge of the Boro box after a defensive handball.
The dead ball was driven in low by Jutkiewicz, but it was claimed low down by Randolph at the second attempt.
Middlesbrough were being forced to defend in numbers and Gardner saw his headed effort deflected behind for a corner.
And St. Andrew's erupted on 79 minutes when Adams fired Blues level with superb finish.
Blues' leading scorer had his back to the Boro goal, before swivelling and firing home a peach of finish which left Randolph with no chance.
Immediately Blues made a change with Vassell sent on for his first game time in more than a year as he replaced Maikel Kieftenbeld.
But the joy didn't last for long. With Blues pushing forward in search of a winner they were caught out on the break.
The ball was sent through to Britt Assombalonga by Wing and he was able to run through with it and slide it past Lee Camp
With the game into its final few minutes Blues were not far away from grabbing what would have been a deserved equaliser, but Jacques Maghoma stabbed the ball just wide of the upright.
Blues (4-4-2): Camp, Colin, Morrison, Dean, Pedersen, Jota, Gary Gardner (Craig Gardner, h/t), Kieftenbeld (Vassell, 79), Maghoma, Adams, Jutkiewicz.
Subs (not used): Trueman, Harding, Dacres-Cogley, Mahoney, Solomon-Otabor.
Bookings: Kieftenbeld (29), Adams (55).
Goals: Adams (79)
Middlesbrough (4-3-2-1): Randolph, Fry, Ayala, Batth, Friend, Clayton, Besic (Downing, 69), Wing (McNair, 87), Howson, Saville, Hugill (Assombalonga, 70).
Subs (not used): Lonergan, Tavernier, Van la Parra, Fletcher.
Bookings: Wing (56).
Goals: Wing (37), Assombalonga (82)
Referee: Graham Scott.
Attendance: 21,420 (1,325 Boro fans).