AITOR KARANKA has outlined his continued frustration with Daniel Ayala’s ongoing ankle problem, and admitted he still does not have a clue when the injury-plagued centre-half will be fit enough to return to training.

Ayala has started just one of Middlesbrough’s last six matches, and did not feature in the squad for either of Boro’s last two games against Bournemouth and Manchester City.

He has been plagued by ankle problems for the best part of a year, but Karanka had initially been led to believe he would be available to return to full training during the recent international break.

However, Boro’s medical staff announced on Monday that Ayala needed at least another week of recuperation, and an increasingly frustrated Karanka is resigned to having to plan without his fellow Spaniard for a prolonged period.

“I don’t know how he (Ayala) is,” said the Boro head coach, ahead of tomorrow’s televised home game with Chelsea. “I have spoken with the doctor, but two weeks ago he told me he was going to start training, and then on Monday he called me and said it would be next week. He is with the medical department and he is working with them. When he is fit, he will train.

“It is frustrating, but as a manager you cannot do anything about it. You just have to wait and train with the players you have on the pitch. You have to forget about the players who are not ready.

“It is frustrating, although it was more frustrating last season when we did not have a replacement and Dael Fry had to play. This season, when we have two or three replacements, it is not a problem.

“I am sure he is frustrated too. As a player, you always want to play. But I don’t know. I have not spoken to him, only to the doctors.”

Ayala’s absence would have been more of a problem had Calum Chambers not been so consistently impressive since making a season-long loan move from Arsenal in the summer.

Chambers sat out the opening five league games of the season, but has started five of Boro’s last six matches, with his only absence being an enforced one as he was unable to play against his parent club.

The 21-year-old has formed an effective partnership with Ben Gibson, with the two young English centre-halves thrusting themselves into contention for a place in Gareth Southgate’s senior England squad thanks to the quality of their performances over the last couple of months.

This was always going to be a make-or-break season for Chambers, but while the former Southampton trainee might have been unable to cement a place in the Arsenal first team, Karanka was always confident he would prove his capabilities at the Riverside.

“When he came here two or three months ago, everyone was talking about how Arsene Wenger had said that he had to play, but there was concern because Dani was playing here,” said Karanka. “I said that time would tell, and when Dani got injured, everyone started saying that we couldn’t win one game.

“But without Dani, we drew with Manchester City and beat Bournemouth, and Calum played very well in both of those games. It is not about individual players, it is about the team, but I am really pleased with Calum because as soon as I called him to come here, I knew he could be an important player for us.”

Chambers and Gibson will resume their relationship when Chelsea visit the Riverside tomorrow, but Karanka could have to reshuffle his back four to deal with the potential absence of first-choice left-back George Friend.

Friend twisted his knee in training on Thursday, and will undergo a late fitness test after he was unable to train yesterday. If he is unable to start tomorrow, Karanka will have to field Fabio Da Silva at left-back or move Antonio Barragan from right-back, with Emilio Nsue slotting in on the right-hand side.

“We’re hoping the extra day will make a difference because we know how important George is for the team,” said the Boro boss. “But if he can’t play, we have other alternatives. We will have to wait another 24 hours to see.”

Karanka also faces a selection dilemma over Gaston Ramirez and Cristhian Stuani, with the pair having made a trans-Atlantic return trip to Uruguay during the international break.

“We have a few doubts about the players who have come from Uruguay,” he said. “Not in terms of their fitness because both of them have trained (yesterday), but they have had a long journey.”