Manchester City have confirmed there is no timescale for Kevin De Bruyne's new injury.
The Belgian missed Tuesday's 2-0 win over Dinamo Zagreb with a groin injury, sustained in the win over Everton last weekend.
He missed training on Monday and City have confirmed the injury.
A City statement said: "The extent of his layoff depends on how well he responds to the rehabilitation programme overseen by the club's medical staff."
De Bruyne has been simply amazing in the opening weeks of the Premier League this season, picking up eight assists for the reigning champions.