Manchester City manager Pep Guardiola admits he left Riyad Mahrez out of the Community Shield win against Liverpool over concerns the player could have potentially fallen foul of doping rules.

The 28-year-old Algerian only returned to training on Friday after leading his country to victory in the Africa Cup of Nations final last month.

However, notwithstanding that tight timescale Guardiola said they were not prepared to risk putting Mahrez in the squad because they did not have full disclosure of what medication the player might have received while he was away.

"Riyad called me just after being (crowned) champion with Algeria and said, 'I want to come back in 10 days, I want to play against Liverpool'. I said, 'You are more than welcome, it's perfect you come'," said Guardiola.

"But we don't have what he took... about the medicine.

"That's why, for doping control, today was a risk because the doctors didn't have it. That's why he wasn't in the squad to play some minutes.

"He could have played some minutes but we could not take a risk because the doctors did not have exactly the medicines.

"Hopefully he will be back next game against West Ham and in the future everything will be normal."