Manchester United have confirmed that Alejandro Garnacho suffered ankle ligament damage at the weekend.
The teenager came on to help his side try and defeat Southampton in the Premier League.
However, a tackle from Kyle Walker-Peters left him in pain and has resulted in a layoff.
Taking to Instagram on Tuesday, Garnacho wrote: “It is difficult to put into words how I’m feeling right now.
“Unfortunately I will not be able to help my team and team mates in the upcoming games in what is a very important part of the season for us at Manchester United.
“I am disappointed to also miss the opportunity to be with my team mates of the Argentinian National Team in what would have been a great and proud moment for me and my family.
“This is part of football and our profession, however, I am already focused in my recovery. God has taught me to never give up and I will make sure I am back stronger than ever!”