Alvarez was withdrawn on 66 minutes with the scores level at 1-1, but late goals from Bernardo Silva and Erling Haaland saw City come from a goal down to win 3-1 and preserve their 100 per cent start to the campaign.
Hammers boss David Moyes had expressed fears in the build-up to the game after Alvarez was late arriving back from international duty with Mexico, who drew 3-3 with Uzbekistan in a friendly in Georgia in the early hours of Thursday morning.
“Edson Alvarez had a delayed flight and returned home at 3pm [on Thursday],” Moyes said in his press conference. “It’s part and parcel of international breaks.”
However, the 25-year-old told reporters in the London Stadium mixed zone that he had been suffering from fatigue, rather than any injury.
That news will be a relief to Hammers fans, with Alvarez having made an outstanding start to life in east London following his summer switch from Ajax and with the the club’s schedule set to intensify as European football returns this week.