A lot of people have asked me this since the arrivals of Matthijs De Ligt and Noussair Mazraoui as we now have a decent amount of top quality options to choose from in defence.
At the moment, it is a lot easier to pick a back line thanks to players like Luke Shaw, Tyrell Malacia and Leny Yoro all being injured as well as the recent departure of Aaron Wan-Bissaka.
While it is highly improbable that all the defenders will be available at the same time, it could be a little problematic for Erik ten Hag to select his strongest back four if that were so.
This is what I think he'll do should everyone be fit.
Right-back
This is a pretty simple one.
Diogo Dalot is the guy I believe the manager will go with as I think he is a big admirer of the Portuguese. Dalot was the player to make that right-back spot his own despite several fans wanting it to be Wan-Bissaka.
Dalot showcased that he is more able to play the way the manager wants due to his ability on the ball, versatility and strengths going forward.
The defender also won Man Utd's Players' player of the year last season after what was a standout campaign for the right-back in which he scored 3 goals and had 5 assists, his most in a United shirt.
But one of his most underrated aspects is his availability.
With the 70+ different injuries and illnesses suffered by United players last season, Dalot was NOT one of them. He was part of a handful of players that were always ready for the manager.
Having a player with that type of reliability is valuable beyond measure in this day-and-age.
He is also one that Erik ten Hag has greatly developed in his two years at United.
He will be our starting RB.
Left-back
When everyone is fit, Luke Shaw.
I still believe that when Shaw is on the field, he is one of the best in the world in his position.
Shaw is strong, quicker than you think, solid in the air, good defensively and has all the capabilities of the modern full-back. As we saw in season 22/23, the defender is also a very able left centre-back which would give ten Hag another option in that position if push comes to shove.
I like this player and when he's there, we see what a difference he makes to our team as he brings that balance to the side. His link up and relationship with Marcus Rashford is also really good.
Is it a coincidence that Rashford's best campaigns came when Shaw was always available and playing down that left flank with him?
But as ever with Shaw, it is his availability that's the issue and we see just how valuable a player he is when he's absent.
Since joining United back in 2014, the England international has missed over 250 games and 1200 days for club and country.
He is injured again.
Shaw missed the Community Shield defeat to Man City because of a problem he had in pre-season training which turned out to be much worse as he is now unavailable for the next month.
It doesn't paint a good image for him that he made himself available for his country but not the start of the season for his club.
However, if he is somehow ready to play for United, I do think that Erik ten Hag will go with the Englishman.
If not, his new signing Noussair Mazraoui is the player to take that spot.
Centre-backs
Lisandro Martinez will start regardless of his partner. Even with the new additions, I believe that the butcher is still our best centre-back.
He covers basically all aspects of the game required by a CB and he's just awesome besides.
Martinez also makes us play in a different and better way particularly out from the back. We know that this is really important in terms of how the manager wants to build up from defence.
As for his partner, Matthijs De Ligt is going to be his main compadre in the heart of defence.
Despite the addition of Leny Yoro, I do think that Erik ten Hag will favour his former Ajax captain as he is more experienced and already understands the style needed. De Ligt has also played with Andre Onana so there's even more of an understanding in defence.
De Ligt is also a pretty good defender who will definitely push the line up and allow United to squeeze the opposition in their own half.
And he is a leader and winner besides.
We don't have too many of those in our line-up so to have someone like that, it will be all the better for the team.
This doesn't mean that Leny Yoro won't get much game time. With Erik ten Hag being a manager who takes every competition very seriously, I'd imagine that we would plan to go deep in the domestic cups and the Europa League on top of the 38 league matches.
This means that rotation will be necessary which gives the manager the option to change his defence (and team) throughout the course of the season.
All three of Martinez, De Ligt and Yoro play in a similar style or at least allow the general playing style of the team to stay the same. In this case, it won't matter which combination of centre-backs ten Hag goes with as the football will remain the same.
Yoro is also the youngest of the three at 18 so that inexperience factor may come into the manager's thoughts as well.
Furthermore, Thursday-Sunday football is quite demanding so he will need his entire squad for this campaign.
I expect to see a lot of Leny Yoro and everyone else in the squad.
Final Thoughts
It may not be the best defence you'll ever see, but I feel a lot more confident now knowing that we have so many good options.
Should the need arise, there are also the likes of Harry Maguire, Victor Lindelof, Jonny Evans, Tyrell Malacia and youngster Harry Amass who could come in and do a job while allowing for rest and rotation for those who need it.
The only real issue ten Hag and United could have is injuries. It has already begun.
What do you think will be United's starting back line when/if everyone's available?
Background Image: Erik ten Hag during the FA Cup semi-final against Coventry City | Image credit: Getty Images via Goal