#1 Eric Bailly and Marcos Rojo
For all the criticism he bags, Marcos Rojo is actually a solid defender who gives his all for the team. The Argentine is an absolute warrior and absolutely never shies away from a challenge- something that often lands him in trouble.
And with Eric Bailly alongside him, United could prove to be one of the most difficult teams to break down. With the 2 of them at the back, it's almost as if United goes out for war and not exactly a football match.
In Jose Mourinho's first season, Eric Bailly and Marcos Rojo were afforded the chance to play together for quite a while as the others were recuperating from injuries and United were as solid at the back as they have ever been in the recent past.
Since they've already proved that they can do it together, Marcos Rojo and Eric Bailly should be United's go to centre-back pairing for the season. Let's see if Jose agrees now.