Manchester City manager Pep Guardiola expects winger Leroy Sane to miss “six or seven months” with a knee injury.
Sane, 23, tore his anterior cruciate ligament and went off after just 13 minutes of Sunday’s Community Shield win over Liverpool at Wembley.
The German, who was linked with a summer move to Bayern Munich, is set to have surgery in Barcelona next week.
“It is incredibly bad news,” said Guardiola before the champions’ Premier League opener at West Ham on Saturday.
“I don’t know how long he will be out. Normally this kind of injury is six or seven months – hopefully February or March.”
Meanwhile, Guardiola confirmed winger Riyad Mahrez has been cleared to play against the Hammers after being left out of the Community Shield because of fears he could fall foul of doping rules.
City had concerns over medicine the 28-year-old took while at the Africa Cup of Nations in July, when he captained Algeria to the title.
Guardiola also confirmed midfielder David Silva will be City’s captain this season – his last at the club – after centre-back Vincent Kompany’s departure at the end of last term.