Ilkay Gundogan started pre-season training in a protective mask after going under the knife to correct a deviated septum.
The midfielder had the surgery — which had been planned for some time — after Germany were dumped out of the World Cup.
Gundogan arrived back at Manchester City for pre-season training with the headgear, which is said to be a precautionary measure.
The surgery was performed to aid his breathing and the 27-year-old has joked he resembles fictional vigilante Zorro.
Gundogan is available to play in Sunday's Community Shield against Chelsea at Wembley, although Pep Guardiola is unsure how many of his senior squad are available to start.
City's midfield fulcrum, Kevin De Bruyne, will be at the final but is not due to start training again until Monday.
Youngster Phil Foden is pushing for inclusion after a fine performance against Bayern Munich in Miami last weekend.
Meanwhile, England pair Kyle Walker and Fabian Delph returned to City training a few days ahead of schedule on Wednesday.
