The midfielder was in action for his country in World Cup qualifiers against Venezuela last Friday and then Uruguay five days later.
In an update on players on United’s official website following a session at their training ground on Thursday, the club said: “Casemiro was absent, having remained in Brazil, on the club’s advice, to recover as swiftly as possible from a small issue picked up while playing for his country.
“He will be unavailable for Saturday’s game with the Blades but is expected back at Carrington early next week to resume training, although he is suspended for the Champions League encounter with FC Copenhagen at Old Trafford (on Tuesday), after being sent off in the defeat to Galatasaray.”
United also revealed Raphael Varane was working with the squad again after being absent for the 2-1 win over Brentford prior to the international break.
And the same applied to Sergio Reguilon and Sofyan Amrabat – Reguilon has been sidelined for United’s last four games, while Amrabat sat out Morocco’s matches against Liberia and Ivory Coast.
Luke Shaw, Tyrell Malacia, Lisandro Martinez and Aaron Wan-Bissaka are others who have been out of action due to injury, while Jadon Sancho has been training away from the first team “pending resolution of a squad discipline issue”.