Centre-backs: Eric Bailly and Chris Smalling
Eric Bailly is undoubtedly United's best defender but despite being fully fit, he has not featured in their last 5 games, apparently due to a dental problem.
However, the strength the West Ham attackers possess may cause Mourinho to re-think his decision and include the Ivorian in the line-up. Marko Arnautovic is expected to start as the central striker and after settling his differences with David Moyes, Andy Carroll is expected to play a part as well.
Both of them are known to physically outplay their markers and it may require Bailly's rugged aggression to contain them.
One defender who has been not been plagued by injuries and has been an ever-present this season has been Chris Smalling. Despite being prone to the occasional error, he has often stepped up at times when it has mattered the most.
He has also been a threat on the other end of the pitch and has found the back of the net 4 times this season. We expect Smalling to keep his place in the team.