Edinson Cavani will miss Manchester United's game against Newcastle on Saturday because he will be in self-isolation.
United's new striker, who joined on Deadline Day, has been isolating since his arrival from France on October 4.
As a result of the 14-day quarantine period, he is not allowed to feature in the Premier League match and will train with his United teammates when his quarantining ends on October 19.
Manchester United play their Champions League group stage opener against Paris-Saint Germain in France on October 20.
United wrote in a statement: "The Uruguay international will be free to play against his former club Paris Saint-Germain in the Champions League, though, if deemed fit and ready for action."
United's Deadline Day signing Alex Telles will be allowed to feature for United because he was in a protected bubble with Porto. The UK government allows restriction exemptions for elite athletes.
United will also be without forward Anthony Martial for the trip to St James' Park as he is serving a three-match suspension.