Kevin De Bruyne is set to miss Manchester City's next three games after testing positive for COVID-19.
The midfielder returned a positive test on Wednesday and will have to spend a spell in isolation.
He has already been ruled out of Sunday's game against Everton at the Etihad Stadium and is also set to miss the Champions League clash with Paris Saint-Germain on Wednesday and the game against West Ham at the Etihad on Nov. 28.
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"Unfortunately Kevin got a positive COVID test in Belgium and needs 10 days [isolation]," Pep Guardiola told a news conference on Friday.
"Two days ago he told me he was positive.
"Now he is positive he has to recover well and go with as few symptoms as possible.
"The health of the human being is more important than anything else.
"So one person tests positive, be careful because still now people are dying about this pandemic situation. He was vaccinated so he was more protection.
"Hopefully he will have minor symptoms. The important thing is that he comes back when he is negative, he will start to train with us as soon as possible again and come back but it's not about any concern about the rhythm or what we are going to miss.
"The person is more important. When someone tests positive we have to be careful and we have to help him and he has to be isolated at home and hopefully it will go well."
Jack Grealish is a major doubt for the Everton game after withdrawing from the England squad with injury but Guardiola is hopeful Phil Foden will be fit after the 21-year-old picked up a knock while on international duty.
Raheem Sterling should be available despite leaving the England squad because of personal reasons.
Asked on Friday about Sterling's future after being linked with a move to Barcelona, Guardiola was quick to shut down the questions.
"Don't ask me from now on until the transfer window is open because I'm not going to answer them," he said.
"Mine and Raheem's focus is on the games, I'm not going to answer any questions about what's going to happen in the future because I don't know what's going to happen."