AITOR KARANKA claims his players’ “lack of intensity” was the key factor in their first Premier League defeat of the season.

Karanka watched goals from Christian Benteke and Wilfried Zaha condemn Middlesbrough to a 2-1 defeat at the hands of Crystal Palace, and while Boro rallied when Daniel Ayala scored at the end of the first half, the Teessiders produced their worst league display of the season as their unbeaten record disappeared.

Having started slowly, they were undone by a succession of defensive errors, and Karanka was unhappy with his players’ lack of drive and focus as Palace gained the upper hand in the first half.

He made a double substitution before the hour mark in an attempt to change things – something he tends to be reluctant to do – and while Boro finished strongly as they threatened to claim a second equaliser, they were ultimately unable to claw back their second-half deficit.

“We’ve lost and we have to learn,” said Karanka. “This has been a good example of what can happen if we do not play with the right intensity. We are in the Premier League, and it will be a mistake if we do not play with the right intensity.

“If we have arrived to this game unbeaten, it is because we have played the first three games with an amazing intensity. In the first half, we didn’t have the right intensity, and that made it impossible to come back in the second half. It is a good example of what will happen if we do not have the right intensity in the Premier League.

“We had problems last season in the Championship when we dropped our intensity, but we had all the games to recover the points. In this league, we have to know that for 90 or 95 minutes every game, we have to play at 150 per cent.”

As well as lacking intensity, Boro also paid a high price for some uncharacteristic defensive errors, with full-back George Friend especially culpable.

Friend failed to close down Zaha as he crossed for Palace’s opener, and misdirected an attempted back-pass at the start of the second half, enabling Zaha to slot home his side’s second.

Friend was clearly distraught at his second-half error, but with the full-back having played a pivotal role in last season’s promotion success, Karanka was not about to start pointing the finger of blame.

“It is not the moment to say anything,” he said. “George is the first one who knows he made a mistake, but if I have to complain about George Friend, it will be the last thing I do.

“I always say that Grant (Leadbitter) is the character of this team, but George is another one. He is the captain and I can’t blame him for this.”

Karanka opted to leave Gaston Ramirez on the bench for the opening 57 minutes, with the Uruguayan making a considerable impact after he came onto the field to replace Viktor Fischer.

Ramirez only returned from international duty with Uruguay on Thursday, but Cristhian Stuani, who made the same trip, started on the right-hand side of midfield while his compatriot was relegated to the bench.

Karanka thought long and hard about his team selection, but felt Ramirez was showing signs of fatigue as he trained at Rockliffe Park on Friday.

“I was with him on Friday, and he knew and I knew that he wasn’t ready to play the full 90 minutes,” said the Boro boss. “That’s why I kept him on the bench. I thought it would be important when he went on the pitch.”

Karanka also named Marten de Roon on the bench, with the £12m summer signing finding himself out of the starting line-up as a consequence of Adam Forshaw’s strong performances this season.

“Marten has been waiting for his opportunity – he has been injured - but Adam Clayton and Adam Forshaw have been playing well,” said Karanka. “That was why he had to wait on the bench.”