With Ben Gibson almost a certainty to start, our writers debate which other Boro centre-back should partner him on Sunday.
Middlesbrough return to Premier League action on Sunday against Watford looking for a first home win since April.
Aitor Karanka has a clean bill of health - captain Grant Leadbitter aside - and has plenty of decisions to make in terms of his team selection.
Ben Gibson is one of three Boro players to have played every single minute of top-flight action this season, along with Antonio Barragan and Stewart Downing.
But should partner him in the heart of Boro's defence?
On-loan Arsenal defender Calum Chambers has played the last two matches , dislodging last season's regular Daniel Ayala. But with Bernardo Espinosa fit again and still awaiting his Boro debut, there are plenty of options at Karanka's disposal.
Anthony Vickers
When it comes to the central defensive duo it is not so much a question of which two play, but who starts alongside Ben Gibson.
Gibbo is a given for me. He has been a first-team fixture and played every single minute in the Premier League this term for a reason. He has found his feet quickly at the higher level.
During Boro’s baptism of fire, he has remained unflustered and while he is up against fitter and faster opponents every week now, he has got stuck into the task with relish and is learning lessons from every game.
He is calm, commanding, can cope with the physicality of the elite division and shows great leadership in a position often under pressure. I think he will get better too.
So that position in Boro’s rearguard is nailed down. So who to start alongside Gibbo at the back?
Personally I would stick with Calum Chambers. After a shaky start against Spurs he has grown into the role and he played well at West Ham - and so should keep the shirt.
The on-loan Arsenal man didn’t have the best of starts in a torrid first half against Spurs - but who did? He was pulled around, taken out of position and skinned once or twice, and some supporters had him written off before the break.
But he is talented defender. And despite his youth, when it comes to the Premier League he is the most experienced on the Boro books.
He’s played over 50 games in the top-flight for Southampton and Arsenal so he is no mug, and that kind of nous is at a premium in a relatively rookie Boro team.
And he has played with Gibbo before in the England Under-21s, so there is a fledgling relationship there. Against West Ham, the pair worked well together. They deserve the chance to work on that.
Yes, there is a strong case for Dani Ayala to play and I wouldn’t be disappointed at that. The well-drilled pair were superb together in the Championship and if that is the chosen two, that’s fine.
But Ayala missed most of pre-season with an ankle injury and on his return played three games in quick succession and struggled at times.
He looked sluggish as he watched the cross sail in for Christian Benteke to score against Crystal Palace and was out of sorts and had a bit of a ‘mare at Everton, so perhaps it was a good time to take him out to regroup.
Now he will probably have to wait for his chance to return. That is the Karanka method.
And Espinosa? He’s fighting fit and we’ve heard good reports from the ressies, but it would be a surprise if he started before even a minute from the bench. His time will come.
Jonathon Taylor
I'd agree that Ben Gibson is a shoo-in. He's been the quickest of last season's award-winning back four to adapt to Premier League life.
As a result, he's being talked about in England circles - and deservedly so. Burnley's Michael Keane got the nod during the last squad, but Gibson's time will come.
As for who should partner him at the back, it's far less clear-cut. It's a 'toss a coin' job at the minute.
Calum Chambers has played the last two games, and although he was much improved against West Ham, I've not been 100% convinced yet. That's not to say I won't be in time.
But he had a dreadful opening 45 minutes to his debut against Tottenham, in which he almost gift-wrapped a third goal to Spurs which would have put the visitors out of sight.
The rest of the team didn't perform, granted, but defensively he seemed a tad indecisive. I was pleased to see he was much better against West Ham - in what was Boro's best display over the last few weeks.
Had the international break not have arrived, I would have said Chambers should start again this weekend - but he's not been training with the team for the last couple of weeks.
As a result, I think the Watford game is the ideal time to bring Daniel Ayala back into the fold - with the Spaniard back up to speed following his frustrating pre-season.
Taking Ayala out of the team for the last two games was a surprise, but not necessarily the wrong decision. Boro had looked shaky at the back, and this is a player who has only just really shaken off his troublesome ankle knock.
But in Ayala and Gibson, Boro have flourished over the last two seasons - and I'd like to see them both reunited at the Riverside.
Up against Troy Deeney, I think Ayala would relish the physical battle a little more than Chambers too.
As for Bernardo Espinosa, his wait continues. I've had the pleasure of seeing him a couple of times for the Under-23s, and there does look to be a good player in there.
He's vocal, he's an organiser and he's a real unit. Once he gets his Boro chance, it might be difficult to dislodge him from the starting line-up.
But for now, Ayala has more credit in the bank - so I'd start him against the Hornets.
