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Two goals in two minutes saw Boro slip to a dismal 2-0 defeat at Sheffield Wednesday on an afternoon when their promotion rivals also dropped valuable points.
Quick-fire goals from Atdhe Nuhiu (pen) and Will Keane saw the Teessiders slip to a seventh league defeat of the season on an afternoon to forget at Hillsborough.
The defeat was less costly than it could have been as table-topping Derby were beaten at Fulham, but it was an opportunity after a lacklustre Boro display.
Aitor Karanka made five changes from the team that beat Bolton 1-0 win at the Riverside on Tuesday, with left-back James Husband making only his second league start of the season.
There were also starts for Kenneth Omeruo, Dean Whitehead, Adam Forshaw and Kike in a surprise 3-5-2 formation, with George Friend, Grant Leadbitter and Lee Tomlin named on the bench.
It was the same system that saw Boro clinch a late 2-1 win against Blackpool on a battered Bloomfield Road surface earlier this month, and the equally-poor Hillsborough pitch surely forced Karanka's hand again.
There was no place in the Boro squad for trio Ryan Fredericks, Mustapha Carayol or Adam Reach, with Boro perhaps wanting to keep some players fresh for Tuesday's home match against Millwall.
Boro started on the front foot and had a penalty appeal turned down inside three minutes when Albert Adomah was seemingly fouled by Claude Dielna, but referee Stephen Martin waved away the protests.
On 10 minutes it was Sheffield Wednesday on the front foot, attacking the Leppings Lane End that housed 4,500 travelling Teessiders.
Striker Atdhe Nuhiu caused panic in the Boro ranks and fed left winger Jacques Maghoma, but the sting was taken out of his shot by Adomah and the ball fell nicely into Dimi Konstantopoulos' hands.
The hosts continued to threaten moments later as Lee's shot cannoned out for a corner, before right-back Liam Palmer fired wide from 25 yards.
With Kike and Patrick Bamford increasingly isolated up front, the Owls came close on 23 minutes as Palmer hit a long diagonal towards Nuhiu on the penalty spot, and the big man in turn teed up Will Keane - but his header landed on the roof of the net.
On the half hour mark Boro poured forward and Adam Clayton hit a speculative 25-yard shot wide, before looking down to the crumbling Hillsborough pitch in disgust.
The game was stopped on 33 minutes when Bamford clashed heads with Wednesday defender Kamil Zayatte, and the tackles started to fly in once it was restarted with Whitehead and Forshaw both making their presence known in midfield.
With both sides struggling to find their feet on a worn surface, the Owls came close on 42 minutes as the ball was fed to front man Nuhiu, but Husband came in with a vital challenge before the striker could set himself.
Then on 44 minutes Ben Gibson's raking pass over the top set Forshaw free, but the former Brentford man's attempted lob bounced over the top of the crossbar - much to the relief of Owls goalkeeper Kieren Westwood.
At the other end Dielna called Konstantopoulos into action before the break, firing a left-footed shot towards goal that was well held by the Greek stopper.
HALF TIME SHEFF WED 0 BORO 0
Boro carved out a great chance on 48 minutes as Adomah fed Bamford, and the on-loan Chelsea man put a wonderful low delivery across the face of goal - but the ball was just in front of Kike, who was lurking at the back post.
At the other end Dielna scooped a high cross into the Boro box, but with Nuhiu looking lively, Tomas Kalas hacked clear before Lewis McGugan lashed wide of the target.
On 52 minutes Wednesday were awarded a penalty as the ball appeared to bounce up and hit Omeruo on the arm, after good work from Nuhiu.
And it was Nuhiu who converted from 12 yards, drilling the ball low into the corner beyond Konstantopoulos' grasp.
That was Nuhiu's fourth goal against Boro in his last three matches, and Hillsborough was up in celebration again two minutes later.
Omeruo gave away cheap free-kick near the corner flag, and Nuhiu headed McGugan's free-kick off the post - but Will Keane reacted quickest in a goalmouth melee to nod the Owls further in front.
On 57 minutes Tomlin and Leadbitter came on to replace Omeruo and Whitehead, while Wednesday brought on Sam Hutchinson to replace Keiran Lee.
The home side should have extended their lead even further on 63 minutes when Keane was played through on goal by McGugan, but the striker's tame shot was easily saved by Konstantopoulos.
There was a brawl inside the Owls box on 64 minutes after Bamford was fouled just outside the box, with Tomlin and Jose Semedo both shown a yellow card for their role in the melee.
Boro spurned another opportunity on 70 minutes when Forshaw beat his defender on the left and put a ball towards the back post, but Bamford's downward header was held by Westwood.
On 72 minutes Yanic Wildschut replaced Forshaw and slotted in on Boro's left wing.
Then on 79 minutes the Owls came close to adding a third, with Nuhiu turning in the box but Kalas came in with a vital block at the final minute.
Moments later Boro should have pulled a goal back when Bamford teed up Kike, but with the open goal gaping, Palmer somehow got back to divert the Spaniard's shot wide of the post.
On 87 minutes Boro were again chasing towards their own goal when Nuhiu held the ball up and passed it to Chris Maguire, but his cross missed everyone and went out for a throw.
Then two minutes later Stevie May caused chaos within the Boro defensive ranks, with Konstantopoulos and Gibson managing to hack the ball out for a corner.
The resulting corner by Maguire was punched away by Konstantopoulos, before Dielna's swinging cross looped dangerously over the top.
With the clock ticking down Bamford wriggled away from his marker but his cross was headed clear by Zayatte, before Tomlin found Kike - but the Spaniard lost his feet and the ball dribbled out for a goal kick.
On 92 minutes Kike sent Westwood sprawling across his goal with a right-footed shot, but it crept wide as Boro limped to a second defeat in three matches.
FULL TIME SHEFF WED 2 BORO 0
Boro: (3-5-2) Konstantopoulos; Kalas, Omeruo (Leadbitter 57), Gibson; Adomah, Whitehead (Tomlin 57), Clayton; Forshaw (Wildschut 72), Husband; Bamford, Kike. Subs not used: Ripley, Friend, Nsue, Woodgate.
Attendance: 23,774
