Manchester City boss Guardiola left Algeria forward Mahrez out of his squad for the Community Shield last weekend as a precaution in case he was called for testing at Wembley.
Mahrez, 28, underwent a minor procedure to aid his breathing after helping Algeria win the Africa Cup of Nations last month. City’s medical staff did not have full details of all the treatment prior to Sunday’s game and did not think he should be risked.
But the club have now cleared up the matter and Mahrez will be available for Saturday’s Premier League opener at West Ham.
Guardiola said: “He had a little surgery after the African Cup on his nose so he could breathe better.
“It’s a normal situation (but) the doctor, not from the national team, didn’t send the necessary (information). That was the only reason why (he did not play). We didn’t have it in the right moment.
“It was a precaution, we had to be careful. It was better not to use him.
“But after the last week, anti-doping have made the test, everything is clear and everything is fine. He can play.”
Mahrez had a mixed first season at the Etihad Stadium after his then-club-record £60million move to City from Leicester in the summer of 2018.
With competition for places from the likes of Leroy Sane, Bernardo Silva, Raheem Sterling, David Silva and Kevin De Bruyne, he struggled to command a regular place.
After this week’s news that Sane is facing a lengthy lay-off with a knee injury, however, Mahrez may get more opportunities to step up.
Guardiola said: “The quality (we get) from Leroy we don’t have it (without him). A little bit Sterling has it but the special quality of Leroy you can’t find it around the world, that attacking the space, that speed.
“Riyad has another (quality), so he’s not a substitute for Leroy.
“My opinion during the first few games, the performance of Riyad, I was quite impressed. He didn’t play too much because in his position was one of the best players in the league in Bernardo and of course Sterling.
“But with Leroy absent, we have more space and a lot of games, one less forward player, so he is going to play. The way they are training, I’ll try to let everyone play.”
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