Emmanuel Latte Lath came off the bench to score Middlesbrough's third goal of the game
Middlesbrough scored four goals in a dominant performance to pile the pressure on struggling QPR and their boss Marti Cifuentes.
Two goals in four first-half minutes from Riley McGree and Tommy Conway put the visitors in control at half-time.
Boro keeper Seny Dieng pulled off a string of stunning saves to preserve that two-goal lead going into the break, but Anfernee Dijksteel's own goal gave the home side hope with 20 minutes remaining.
Emmanuel Latte Lath and Dan Barlaser came off the bench to net, though, and secure the points for Boro late on.
The second-bottom R's have now failed to win any of their eight home games, while Boro moved up to seventh in the table, only outside the play-off spots on goal difference.
Super subs make the difference
Having had much of the ball in the opening half an hour with little to show for it, Middlesbrough burst into life as the lively Ben Doak set up McGree at the near post for his first goal of the season.
Conway rounded off a fast team move as Luke Ayling's line-splitting pass found Finn Azaz in space on the right to cross for the Scottish striker to finish beyond Paul Nardi.
QPR created many chances of their own and would have been on the scoreboard sooner if it wasn't for a fine display from Boro goalkeeper Dieng.
The away side had to withstand periods of QPR pressure but also had long spells where they had control of the game.
Boss Michael Carrick sent on Dijksteel, Latte Lath and Barlaser, with all three making an impact at both ends of the pitch.
Defender Dijksteel's unfortunate own goal came from a QPR corner, before Latte Lath twice rounded Nardi to restore the away side's two-goal lead.
Barlaser's curled effort into the bottom corner was assured and added more gloss to the result for the travelling fans five minutes into added time.
The home side's misery was deepened by a knee injury to attacker Ilias Chair who was replaced at half-time and joins a lengthy list of absentees.
'We had to work for the win' - Carrick
QPR are without a win at Loftus Road so far this season
QPR boss Marti Cifuentes, speaking at the post-match press conference, said:
"In a few minutes we conceded two goals that we should defend much better and suddenly we're 2-0 down in minute 35.
"I think we reacted after that and we created three good saves for the keeper [Seny Dieng]. We knew that by scoring one goal before half-time could give us some help in how to approach the second half but the keeper was brilliant.
"We were trying to push in the last minutes [with the score 2-1] and we were risking more and more.
"A counter, a very good player that comes from the bench in a situation that we knew could happen when we are risking the match, then for me the game is kind of over."
Middlesbrough boss Michael Carrick said:
"We had to work for it, to be honest. I thought we played some really good football in spells, maybe not as long as we wanted to.
"We could have made it a little easier for ourselves but credit to QPR, they made us work for it.
"But I thought the quality of some of the goals and some of the football was really good and we showed a bit of character and composure in the second half to see the game through."
