LONDON:Manchester City manager Pep Guardiola believes John Stones has the ability to become one of the best defenders in the world but said he will not reach his potential until he stays fit for long periods.

Stones last featured for City in a 2-1 Premier League defeat by Manchester United last month and has been restricted to just 12 club appearances this season.

The 25-year-old is likely to return to City's starting lineup for the FA Cup third round match against League Two side Port Vale on Saturday after recovering from his third thigh injury of the campaign.

"He has the conditions to do it, but to be the best central defender you have to play one entire season, every three days being there," Guardiola told a news conference. "I don't know why he has not been able to play regularly. We try to help him. We have tried to do the best to help him since the first day of the three and a half years we have been here. We do everything for him. It depends on him. It's in his hands and in his head to become one of the best."

In the absence of Stones, City have been forced to play Brazilian midfielder Fernandinho and 18-year-old Eric Garcia in centre back positions over the festive period.

Barcelona academy graduate Garcia has impressed Guardiola with his tactical maturity, having helped City to victories over Sheffield United and Everton.

"Eric is so clever," Guardiola added. "Everything you say to him, he understands, he doesn't need more time to understand. Life is about opportunities. We are delighted with how he has taken his. He's helped us in tough moments."