Daniel Ayala and Bernardo Espinosa are both available to play for Middlesbrough in their Premier League match at West Brom on Sunday, head coach Aitor Karanka has confirmed.

Ayala made his comeback from injury in the extra-time EFL Cup loss to Fulham on Wednesday and is in line for his first Premier League appearance of the season, while Espinosa could make his debut for the club.

Full-back Antonio Barragan has been deputising in the middle of the back line with Espinosa and Ayala unavailable and Karanka highlighted Ayala's return as a "huge boost".

"I was a little bit concerned after a long time without playing," said Karanka. 

"And it was the kind of game where it was box to box, but he finished well and it's a huge boost."

"Pre-season in Marbella was really good for [Espinosa]. The medical department was really impressed. Now he's played three [reserve team] games in last 10 or 15 days.

"He played 45 minutes in his first game, 70 last Monday and on Thursday he played all the game. So for that reason I'm really pleased because I can feel he's desperate to play."

Despite Ayala and Espinosa being in the mix for selection, Karanka remains keen to sign another defender before the transfer window closes on Wednesday, but he would not comment on reports Hull City's Harry Maguire is his top target.

"We are trying to bring the right one but again we are not in a hurry, we are not going to make mistakes," Karanka said. "If something good appears we will bring them in, but we won't bring them in for the sake of it.

"That's the only position we are trying to bring someone in but I said [that] three or four weeks ago and nothing [has happened]. The club is working with a list of players. I know they are working and I am thinking about the game on Sunday."

Brad Guzan will continue in goal as Victor Valdes is still recovering from a hamstring injury and Karanka has a problem at left-back as George Friend and Fabio Da Silva are injured too.

"Fabio for sure isn't going to play," Karanka said. "Friend is a muscle injury but I don't know. 

"I don't like to take risks with muscle injuries, especially with an international break, but let's see tomorrow. I have options. We have two left-backs, three with James Husband, but he is injured.

"So the player who plays there will be playing in a different position. Maybe I can change the shape but I don't know. We have players to cope."