Nemanja Vidic has been discharged from hospital, with Manchester United confirming the club captain suffered concussion during Sunday's game against Arsenal.
The centre-back collided with team-mate David De Gea during the 1-0 victory over the Gunners and was immediately replaced, leaving the field at Old Trafford with a bloodied face.
Vidic was sent to hospital for examination by the club but has since returned home.
In a statement, the club said: "Nemanja Vidic has been released from hospital after suffering concussion."
While not due to play again until November 24 when United visit Cardiff in the Premier League, no time-scale has been placed on the 32-year-old's return.
While there is no mandatory period for Vidic to rest, United's medical staff will need to be satisfied the defender has fully recovered before he is allowed back on the pitch.
The injury comes at a time when how players who suffer from concussion are treated is a major debate.
Earlier this season, Tottenham goalkeeper Hugo Lloris played on despite having been knocked unconscious during his side's match against Everton.
Spurs manager Andre Villas-Boas was heavily criticised for his decision not to substitute the keeper, although he would later defend his actions, insisting he acted on advice from club doctors.
Lloris was rested over the weekend as a result of the concussion and placing a time-frame on recovery for any player who suffers such an injury is impossible.
"There is no hard and fast rule in how long a recovery can take," said Dr. James Gyurke from ImPACT Applications.
"Everybody reacts to it differently. In a concussed state the recovery period should be viewed as occurring over several days to weeks, not a single day. There is no prescribed timeline for someone."