A goal in either half condemned Michael Carrick's side to defeat at the hands of Queens Park Rangers.
It was another frustrating afternoon for Boro, who dominated large parts of the contest, but found visiting goalkeeper Amir Begovic in superb form and were unable to find a way onto the scoresheet.
Possession
39%Shots
11Shots On Target
3Corners
5Fouls
111
0
Cards
2
0
It was a real stop-start opening to proceedings with two lengthy stoppages for injuries inside the opening 15 minutes. Darragh Lenihan and Andre Dozzell clashed heads while Emmanuel Latte Lath received treatment for a hand injury.
The game soon sprung into life, though, and it was Boro who were on the front foot with some good passing and quick movement. Latte Lath was crowded out when he looked to shoot and Sammy Silvera sent a shot just wide of the mark.
Morgan Rogers also played in Isaiah Jones, who was denied by a good save from Asmir Begovic. Latte Lath forced a save from the QPR goalkeeper and Morgan Fox hacked the ball clear.
But it was the visitors who took the lead with a goal from out of the blue. Dozzell was the man who took aim from 25 yards and lashed the ball into the top corner with a strike that left Seny Dieng with no chance.
Boro were almost back on level terms before the break, but Begovic pulled off another good save to deny Lenihan after a Jonny Howson free-kick.
Lukas Engel
Boro started the second period on the front foot, and Latte Lath was denied again by Begovic from the restart. Jones also saw a crucial pass cut-out after a quickfire break by Boro.
Carrick introduced Sam Greenwood from the bench to make his debut, and he was joined by Riley McGree as Boro looked for a route back into the game.
Begovic was in imperious form for the visitors, though, and he denied Latte Lath once again after good work by Silvera.
Lewis O’Brien was next to make his debut when he was introduced to proceedings, and he was joined by Josh Coburn for the final 20 minutes or so.
But things immediately got worse for Boro when Jack Colback smashed the ball home from the middle of the box to make it 2-0 to the visitors.
As the clock ticked down, Greenwood saw a shot deflected wide of the mark after good work by McGree.
Middlesbrough: Dieng, McNair, Fry, Lenihan, Engel, Howson, Hackney, Silvera, Rogers, Jones, Latte Lath
Subs: van den Berg, Barlaser, McGree, Gilbert, Coburn, Glover, O'Brien, Greenwood, Bilongo
QPR: Begovic, Kakay, Cook, Fox, Smyth, Field, Colback, Paal, Dozzell, Armstrong, Chair
Subs: Clarke-Salter, Willock, Archer, Dixon-Bonner, Larkeche, Kelman, Duke-McKenna, Adomah, Kolli