Huddersfield took another big step towards securing their place in the Championship play-offs, and damaged Middlesbrough's hopes in the process, with a 2-0 win at the Riverside Stadium.
There was drama midway through the first half when Boro goalkeeper Luke Daniels caught Sol Bamba's backpass, but though the Terriers could not capitalise from the indirect free-kick, they took the lead when Naby Sarr headed in their 20th set-piece goal of the season (41).
Boro offered an increased threat after the break, but saw their fate sealed with an hour gone, when Jordan Rhodes rounded off a sweeping counter-attack and plundered the second.
The result sees Middlesbrough drop to ninth, three points off the top six with four games to play. Huddersfield stay third and continue to trail second-placed Bournemouth by four points, albeit having played two games more.
How Middlesbrough's top six hopes were hit again
As the high-stakes clash got under way, Middlesbrough's primary threat came from Isaiah Jones, who gave Harry Toffolo a hard time on the right flank, but it was Huddersfield who looked the more likely to draw first blood throughout much of the first half-hour.
From nowhere, they nearly did when Bamba flicked the ball back to goalkeeper Daniels; he caught the ball when it looked destined for the net, leading to Terriers players calling for him to be sent off for denying a goalscoring opportunity.
Yet the laws of the game state the offence is punishable only by an indirect free-kick, and from the resulting set-piece Daniels made a smart save to deny Rhodes.
Four minutes before the break, though, the visitors did strike. Though carrying a knock after an earlier collision with Marc Bola, Sorba Thomas floated a wonderful free-kick to the far post, which was met by Rhodes, who headed into the path of the unmarked Sarr, who scored for the second game in succession.
Middlesbrough improved to an extent thereafter and were first denied a route back into the game when Lee Nicholls held Marcus Tavernier's cut-back, before Tom Lees made a brave block to charge down an effort from Duncan Watmore.
But within seconds, Huddersfield had doubled their advantage. The hosts had been vulnerable to their hosts' counter-attacking capabilities and paid the price when Lewis O'Brien swept the ball out to Rhodes, who slammed in with his weaker left foot.
Boro almost found a late way back, when Riley McGree plucked the ball from within a crowd and struck with power, but his shot came off the crossbar, as for the fourth game in succession, Chris Wilder's men failed to score.
What the managers said...
Middlesbrough's Chris Wilder: "The goals that we have conceded in those three games, four terrible goals. It's not a good time, the timing has not been great for us not to cement a place in the play-offs through three home defeats on the spin. It is still alive. It is going to be a struggle to hide my emotions because I'm not a very good actor. I am deeply disappointed, we fancied it today. We set it up with good performance on Easter Friday (at Bournemouth) and after half an hour I was delighted.
"I am not looking beyond today, I am analysing today, the immediate reaction. And it is one of huge disappointment. They came to counter-attack, sit in and it's not an issue. We had to break them down. It gets decided in both boxes, they defended their goal fantastically well. We didn't risk enough, cross it enough, shoot enough, we didn't manage to pick anyone out from good areas. The second goal was a huge boost for them."
Huddersfield's Carlos Corberan: "My target is to get Huddersfield in the highest position we can. If we can do that then we will be doing a good job. Our points are 73 and my target is to get the maximum number of points we can. We need to focus on getting the maximum number of points we can. The more we have the higher we will be up in the table. That has to be our mentality.
"Every time when you play football you have to go for the games. We will enjoy today, celebrate and from tomorrow we will start the process to recover and focus on the next game. We are working hard to achieve the best position we can in the table."
Man of the match - Jordan Rhodes
Don Goodman on Sky Sports Football:
"I can't believe this man's work today. Don't forget he set up the opening goal and then scored a brilliant one of his own. He has been a constant thorn in Middlesbrough's side."
Micky Gray on Sky Sports Football:
"If managers and coaches who take Jordan on now don't know what his game his, it's a waste of time. His hold-up play isn't the best but when you get him turning and into that 18-yard area, he always wants to score goals. If you provide the service for him, he will score goals for you."
What's next?
Huddersfield are back in action at 7.45pm on Friday April 22, when they host Barnsley at the John Smith's Stadium at 7.45pm, live on Sky Sports Football. Middlesbrough, meanwhile, return at 3pm on Saturday April 23, when they travel to the Swansea.com Stadium to take on Swansea.