Kevin De Bruyne will be out for three months due to a knee injury but will not require surgery, Manchester City have confirmed.
The Belgium international, a second-half substitute in Sunday's 2-0 victory over Arsenal, suffered the injury in training on Wednesday.
City say De Bruyne, 27, has a lateral collateral ligament lesion in his right knee, but does not need surgery.
He missed 12 games in 2016 after injuring the same knee during an EFL Cup semi-final victory over Everton.
He is likely to miss league games against Liverpool (7 October), Tottenham (28 October) and Manchester United (11 November), and the opening Champions League group games.
De Bruyne was integral to the club's record-breaking 2017-18 season, scoring eight goals and providing 16 assists in the Premier League as City racked up 100 points en route to the title.
The Belgium international also enjoyed an excellent World Cup, as the Red Devils finished third in Russia.
He scored a vital goal in their 2-1 quarter-final win over Brazil, and provided two assists, one against Panama in the group stages, and one against England in the third-place play-off.
City failed to sign another midfielder during the summer transfer window but can call upon David Silva, Bernardo Silva, Ilkay Gundogan and Phil Foden as alternative options.
The club face Huddersfield Town this weekend, and will then take in games against Wolves, Newcastle United and Fulham.