Manchester United have confirmed that Alejandro Garnacho damaged ankle ligaments during Sunday's goalless draw with Southampton.
Garnacho, 18, limped off against Southampton following a challenge from defender Kyle Walker-Peters which left him needing treatment.
Garnacho will miss United's upcoming games against Real Betis and Fulham in the Europa League and FA Cup respectively, and will also not link up with the Argentina squad during the international break later this month.