Manchester City's Riyad Mahrez and Aymeric Laporte have tested positive for coronavirus, the club announced on Monday.
City said that neither forward Mahrez nor defender Laporte, now self-isolating, were displaying symptoms.
A club statement said: "Manchester City FC can confirm that Riyad Mahrez and Aymeric Laporte have tested positive for Covid-19.
"Both players are currently observing a period of self-isolation in accordance with Premier League and UK Government protocol on quarantine. Neither is displaying symptoms of the virus.
"Everyone at the club wishes Riyad and Aymeric a speedy recovery ahead of their return to training and the new season."
Mahrez, tweeting in response to messages of support from City fans, said: "Thank you for all the nice messages, I'm good. Stay safe everyone take care of you."
City's first fixture of the new Premier League season is on September 21 when they face Wolves at Molineux but it is unclear if either player will be available.
Under UK government rules, anyone who tests positive for Covid-19 must quarantine for two weeks. As it is unclear when each player began quarantine and thus when they can resume training with the manager’s squad whether he will select them may be in doubt.
City will also begin their Carabao Cup defence later that week. They will face either Bournemouth or Crystal Palace in a third round tie.
Meanwhile, City midfielder Phil Foden could face disciplinary action after video footage emerged of him and another England player allegedly inviting girls to their rooms after Saturday's Nations League win against Iceland in Reykjavik.
The footage came to light on Icelandic outlet DV after the girls shared videos on Snapchat on Sunday.
Like all of the England squad Foden and Manchester United forward Mason Greenwood, who made their senior international debuts in the 1-0 win, were subject to strict Covid-19 health protocols to avoid quarantine rules.
These included not meeting anyone outside of the England squad and staff during the team's stay in Iceland.
Both players were absent from training in Reykjavik on Monday.
England will face Denmark away on Tuesday with manager Gareth Southgate expected to talk about Greenwood and Foden's apparent breach of discipline at a news conference later on Monday. Both face being dropped for Tuesday's clash.