John Stones is quickly learning that Manchester City life under Pep Guardiola will not be easy

The young defender has plenty of potential but still has a lot to learn at the Etihad Stadium

John Stones has his work cut out at Manchester City (Getty)

At Everton, Roberto Martinez called him the best English centre-half since Bobby Moore. Sam Allardyce thought Pep Guardiola might mould him into a new Carles Puyol.

However, on Sunday John Stones looked nothing like Moore or Puyol. He looked lost and before an hour was up in Manchester City’s 3-1 win over West Ham, the world’s most expensive defender was removed.

It was thought Stones was suffering from an eye injury but Guardiola remarked that the 22-year-old was not playing to the required standard. “I saw him tired, I saw him with problems,” said the Manchester City manager.

Stones was replaced by Aleksandar Kolorov, who Guardiola has shifted from left-back to centre-half much as he did with David Alaba at Bayern Munich. Kolarov looks the better bet to start the Manchester derby at Old Trafford a week on Saturday.

Stones is a wonderfully-gifted footballer who may not reach his peak for another eight years. However, playing centre-half for Guardiola is one of football’s most demanding jobs.

With the full-backs pushed up into midfield, there were only three men plus the goalkeeper providing defensive cover against West Ham. In Munich, Guardiola’s goalkeeper was Manuel Neuer, who was almost a sweeper. Willy Caballero is no Neuer.

Fernandinho as the sole holding midfielder will be put under enormous pressure. Against West Ham, the Brazilian was further burdened by an early yellow card while Stones, deep in the West Ham half, was involved in the build up to Raheem Sterling’s opening goal.

Stones is not shy of hard work – last season he ran further in Everton’s defence than Adam Lallana did in Liverpool’s midfield - but Guardiola’s is total football pushed to its extreme.

Last season Stones admitted his game had been affected by the pressures of his abortive move to Chelsea. “It is difficult when there is a lot of speculation and a lot of things happening in your personal life,” he said. “It didn’t just unsettle me, it affected my family as well.” Now, he is having to adapt to a new way of playing the game.

Like Marouane Fellaini at Manchester United, Kolarov is one of those footballers whom everybody expected to leave in the summer but who is flourishing in improbable circumstances. The Croat, however, dismissed the idea that Guardiola had simply sprinkled his magic over him.

“I don’t agree that I have been revitalised under Guardiola,” he said. “I always did my job properly. It doesn’t matter what the papers have been saying, I am doing my job in my seventh year here. It is a different kind of football and at the moment we are happy with him but it is just the start of the season and there are a lot of games to play.”

The switch to centre-half surprised Kolarov not least because Guardiola began the season with three centre-halves for whom the club had paid £119m. But it should not have come as a surprise. Whether switching Javier Mascherano from a holding midfielder to a centre-half at Barcelona or shifting Philipp Lahm into midfield at Bayern, Guardiola tends to seek imaginative solutions from within his own squad.

“On the first day when we came in for pre-season, he tried me in that position,” said Kolarov. “I had never played in that position before. I was a midfielder early in my career. But like the other players, like the full-backs who have to come inside, we have to do what the manager wants.

“I am enjoying playing centre-half because we have a lot of possession and I have more of the ball than I do in the full-back positions,” he said. “The derby is a big game, not just for the city but for the world. There are two new managers at both clubs and I am looking forward to playing in the game.”

If Joe Hart is the big English casualty of Guardiola’s coming - he looks set to make a loan move to Torino - and Stones has not started as smoothly as he would have hoped, the winner in the opening weeks has been Sterling.

Raheem Sterling seems a different player under Pep Guardiola (Getty)

“I didn’t come into the season saying: ‘I want to show everyone’ but just to concentrate of my football,” he said. “I knew if I kept working hard, I would get my chances. I made a promise that when I came back at the start of the season I am going to work hard and be as consistent as I can. Last season was a steep learning curve.”

Sterling knew he would have Guardiola’s backing at least in the opening weeks. The Manchester City manager called him when Sterling was in Chantilly with the England squad to express his support. In another part of France, at the Belgium training camp, Jose Mourinho was doing the same with Fellaini.

“It was a big lift,” said Sterling. “The manager has been in the game a long time, won stuff, worked with young players, worked with great players. He has been a massive help, not just to me but the whole team.

“It is good to have a manager who not only talks to me but makes the whole squad feel welcome, who makes everyone feel they are all one, whether they are starting or not. Everyone is hungry and everyone is ready to run for him and play for him.”