Riyad Mahrez has passed a drugs test and is cleared to play after concerns over medicine he took while on international duty with Algeria, says manager Pep Guardiola.
City were unaware of a medication Mahrez was given while captaining Algeria to victory at the African Cup of Nations, and, as a precaution, he was left out of Sunday's Community Shield win over Liverpool.
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But City manager Guardiola says Mahrez is free to play in the champions' Premier League opener at West Ham on Saturday after undergoing tests with UK Anti-Doping (UKAD).
"One moment last week, anti-doping made the tests and everything is clear and everything is fine," said Guardiola ahead Saturday's trip to the London Stadium.
"Our doctors came to me and said we don't know exactly [what he took] because they know every time they take something, they have to inform the club to make a list and everybody knows it.
"We pass one or two controls every month but in that moment, we didn't have it because he did it in Algeria. That's why I said with precaution that I didn't use him [against Liverpool].
"This week they came and made a test control. He passed and that's why he is ready for tomorrow."
In Mahrez's absence last Sunday, Leroy Sane started for City on the wing but his game was finished after 13 minutes following a coming together with Liverpool right-back Trent Alexander-Arnold.
This week, City confirmed the German international suffered damage to his ACL. Guardiola says he will be out for "six or seven months.
"The quality from Leroy Sane, we don't have it - a little bit with Raheem Sterling, but the special quality of Leroy is not [easy to find] around the world. His attacking the space with quality of speed," Guardiola added.
"Riyad has another one, he doesn't come to make a substitute for Leroy. In my opinion, after reviewing a few games of Riyad from last season, I was quite impressed, it was real good.
"The problem was he didn't play too much because the players in those positions were some of the best players in the league last season - Bernardo Silva and Raheem Sterling.
"But, of course, now with Leroy absent we have more space and a lot of games and one less player upfront so he is going to play."