Why is Casemiro often substituted after 60 minutes?

"Casemiro is often substituted after 60 minutes, is this to protect him from injury or is it tactical? He seems perplexed by the substitution, because he is more influential to the game than others."

This was a question sent into our 'Ask about Man Utd' form.

There are two elements to this – and we are only going to find out whether the latter is correct over the next three games.

First, Ruben Amorim is mindful Casemiro is 33 and his minutes need managing. He has repeatedly used the former Real Madrid man as an example of how players can change his mind about them by their performances, pointing out even Toby Collyer was in front of him at one point last season.

Before the Newcastle game, he said Casemiro is an example for all his squad in terms of how they prepare for games and how to cope, mentally and physically, with the demands they face. That suggests Amorim still views Casemiro as a key figure.

So, the second aspect is this. After the Newcastle game, Amorim dismissed a suggestion he had taken Casemiro off to ensure he was fit for the Wolves game, stating he only dealt with what was in front of him.

However, with seven senior players missing and doubts over Mason Mount, United cannot afford to risk losing any more.

Casemiro might have been surprised to go off against Newcastle, but it would be much more of a surprise if he did not start against Wolves, or Leeds or Burnley after that.

However you look at it, those three are winnable games and could be the difference between United qualifying for the Champions League or not.

I suspect strongly there was an element of trying to keep Casemiro fresh for what lies ahead, even if it weakened Amorim's team in the moment.

This article is the latest from BBC Sport's Ask Me Anything team.