Casemiro requested to leave the game against Venezuela in the second half and was replaced by Andre.
The Brazilian was said to have injured his ankle during the game but the severity of the injury is still unknown.
The injury comes as a huge blow for Man United who are currently having many players with injury at the club.
Casemiro add to Man United injury list
Brazilian captain Casemiro has joined the list of injured players at Man United after sustaining an ankle injury during the international break.
The 31-year-old's condition was disclosed by Brazil manager Fernando Diniz as follows, “He asked to come off due to a blow to his ankle.”
Meanwhile, Gabriel's header in the 50th minute gave Brazil a 1-0 lead when Casemiro left the game on Thursday, but Eduard Bello equalised with an overhead kick in the 85th minute.
Casemiro said after the game as reported by Daily Mail, “Now we have to hold our heads up high and think about Uruguay.
“We wanted to go at them, they wanted to defend and we couldn't break them like we wanted.”
Brazil will face Uruguay in their next World Cup qualifier on Tuesday but will be without the Man United midfielder Casemiro.
Casemiro will join the likes of Luke Shaw, Lisandro Martinez, and Aaron Wan-Bissaka who are all anticipated to miss a significant amount of time.
While the likes of Raphael Varane, Sergio Reguilon, Tyrell Malacia, Kobbie Mainoo, and Amad Diallo are now receiving treatment with the hope that they will soon be back on the field.