Middlesbrough endured a nightmare afternoon in South Wales as their winning run came to an end with defeat at Swansea City.

Compounding matters for Boro and severely denting their play-off hopes, last remaining fit centre-back Dael Fry went off injured too, as Boro finished the game with midfielder Jonny Howson and left-back Neto Borges at centre-back.

Michael Carrick made one enforced change to the side that beat Derby County last time out. Luke Ayling’s injury in that game meant Borges switched to centre-back, with Ryan Giles starting for the first time since defeat to Sheffield United last month.

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All talk pre-match surrounded concerns with Boro’s defence amid the injury crisis. But in a poor first-half that saw them trailing at the interval, it was further up the field where their problems lay. Only the saves of Mark Travers meant they had one positive at the break, that being that they were only one behind.

Jisung Eom scored the goal that separated the sides in the 26th minute. But the home side had been knocking on the door for a long time before time. Far from a side coming in off the back of two wins and fighting for a play-off side, Boro looked miles off the pace.

The biggest issue for them is that the ball just wasn’t sticking. Aidan Morris was unusually sloppy in possession, while Morgan Whittaker proved so lightweight as he failed to retain possession almost every time the ball went anywhere near him. Giles’s confidence looked to be very low, as he struggled whenever the ball was anywhere near him.

Travers was forced to make one decent save before the goal when Eom’s header was deflected off Dijksteel and forced him to change direction. He got down well, as he did when Zan Vipotnik had enough space on the edge to bend one on target.

But there was little he could do with the strike that eventually saw the Swans take a deserved lead.

Whittaker tried a flick inside which sold Marcus Forss short. The Finn wasn’t able to put up enough of a fight for the loose ball as Harry Darling headed forward. Into the path of Eom, it opened up for him to just drive towards goal before curling into the far corner.

Any hope that goal might have sparked Boro into life were short-lived. As their attempts to get into the game proved futile, Swansea kept coming with wave after wave of attack, with Travers forced into a couple of more good stops before the break.

Carrick isn’t one for making half-time changes often. In a sign of his frustration with his side’s first-half performance, he made two here. Off were Giles and Forss, replacing them were January additions Samuel Iling-Junior and Kelechi Iheanacho.

There was an immediate response. Boro enjoyed their best chance of the game to that point four minutes after the restart. A positive Hayden hackney drive found Iheanacho. Riding the challenge well, he sprayed wide to Tommy Conway who, trying to make the most of a rare touch, hit one low across goal. Lawrence Vigouroux looked beaten, but it was just wide of the far post.

If that early chance provided hope, it seemed to quickly evaporate. Boro were really struggling to cope with the intensity of Swansea’s pressing and off-ball work. Put simply, the home side just looked like they wanted it more. On the hour mark, a wide free-kick flashed across Travers’ six-yard box with three Swans players a matter of inches from turning it goalwards and doubling the lead.

They went close again with 20 minutes remaining. An excellent team move resulted in Josh Tymon having space on Boro’s right. He cut back for Eom, who looked certain to have his second, but for Borges’ excellent block. At this point, Carrick had seen enough.

His third change was the introduction of Delano Burgzorg. He replaced Whittaker, who was heavily booed by the supporters of his former side. His return to the Swansea.com Stadium had not been one to remember.

Burgzorg quickly inspired a Boro chance, much like Iheanacho. He hassled to win the ball for Boro in the final third before slipping Conway in behind from a wide position. Trying to hit low across goal, Vigouroux managed to get his leg to it to deny the Boro striker.

But Boro’s afternoon was about to get a whole lot worse. Off the ball and with Boro attacking, Dael Fry sat down as he struggled with an injury. Boro’s last remaining fit centre-back was replaced by Jonny Howson, with the midfielder partnering left-back Neto Borges at centre-back. Boro have had Erik Pieters on trial this week, and this latest setback is likely to improve the 36-year-old’s chances of earning a short-term deal.

Burgzorg’s introduction at least sparked a little life into Boro. For the first time in the game, it was largely being played in the half Boro were attacking for the final ten. Despite that, Swansea’s fight won through, with Boro never really threatening an equaliser despite the efforts.

A defeat that meant Boro failed to capitalise on dropped points for Norwich, Watford and Blackburn, victories for Coventry and West Brom left Carrick’s side five points off the play-off places. Most concerning given what the two sides have left to play for this season, Boro lost the battle in South Wales. They were, quite simply, out-fought.

The defensive injury crisis, which once again brings to focus the decision of Carrick not to sign a Matt Clarke replacement in January, is the obvious concern with longer-term implications. But the manner of this defeat was about far more than a defensive crisis.