Speaking to MUTV before the Aston Villa game, Ralf Rangnick said: “Cristiano Ronaldo is having problems. I wouldn’t say that he is injured, but he has muscular problems.
“I spoke with Cristiano yesterday before training, he told me that he’s had some problems for the last couple of days.
“Minor problems, but in the end, we decided that it made more sense to not take any risks in a game that could easily last 120 minutes, so we just decided to rest him, not play him at all.”
The 36-year-old, who has scored 14 goals in 22 games so far this season, was not included in the matchday squad for the FA Cup third-round clash on Monday.
Manchester United would go on to secure a narrow 1-0 win over the Villa side to advance to the next stage of the FA Cup competition.