Pep Guardiola's biographer reveals why Man City boss could leave club and explains how he's changed during Etihad spell

Marti Perarnau is writing a biography on Guardiola, called The Pep Revolution - which details his eight-year spell at City. The journalist explained that the former Barcelona manager will only leave his current role if he is too tired or because of his family. He added that as his time at the Manchester outfit has progressed, the 53-year-old has mellowed somewhat.

On why Guardiola may leave City, he told Manchester Evening News: "Basically he has the perfect club because of the ecosystem, he has a very good relationship with the players and the players have plenty of energy and desire to win again. I think there are only two factors: the family and his own tiredness after nine years. Perhaps the family say it is too much time in Manchester and the children all grow up. That could happen. If it doesn't happen, who knows. I don't say that Pep won't renew, I'm not sure. I think he will decide between November and February."

On how the Spaniard has changed during his City spell, he added: "I think it's the main change of Pep. More than tactical or other questions, I think the most important change is he's relaxed to the way of competing and also during the matches. During the Community Shield at Wembley, in the worst moments of the match he was relatively relaxed. He learned from the experience of his years at Barcelona and Bayern.

"He started thinking that he needed to push the players until the edge and after years he understood that some players don't need to be pushed until the end - for instance, Kevin De Bruyne doesn't need to be pushed to the edge. Some people need to be more relaxed and more friendly during the match. I think he understood that."

Hot on the heels of leading City to a record fourth-straight Premier League title, Guardiola admitted he was "closer to leaving than staying". The Spaniard is out of contract next summer and club staff are unsure if he will extend his stay there. If he does go, he will leave a City legend after winning six Premier Leagues, the Champions League, and a host of domestic cups, among other trophies. Moreover, the influence he has had on the game and other managers is almost immeasurable.

If Guardiola is to leave, he will be so determined to deliver a record-extending fifth-straight Premier League trophy for City - who are reportedly trying to get him to sign a new contract. On Sunday afternoon, they begin their title defence against Chelsea at Stamford Bridge.