Arsenal right-back Hector Bellerin has been ruled out for four weeks with an ankle injury.
The 21-year-old Spaniard was injured during the the north London derby against Tottenham on 6 November.
“He got injured in the last 10 seconds in a very strong tackle from Danny Rose,” said Arsenal boss Arsene Wenger.
Bellerin, who has played in all 11 of Arsenal’s league fixtures this season, could miss eight games, including the visit of Paris St-Germain.
He will sit out the Champions League trip to Basel on 6 December, as well as the EFL quarter-final against Southampton at Emirates Stadium on 30 November.
Arsenal are fourth in the Premier League as they prepare to face Manchester United at Old Trafford on Saturday (12:30 GMT).
They will assess the fitness of Alexis Sanchez on Friday after the forward scored twice for Chile in a 3-1 win over Uruguay on Tuesday, despite being a doubt before the game.