MANCHESTER -- Pep Guardiola has said John Stones still as work to do to fulfil his potential as the Manchester City defender prepares to go head-to-head against one of his social media critics -- Port Vale striker Tom Pope.
Pope tweeted he would "love to play John Stones every week" because he would "score 40 a season" while watching highlights of the centre-back struggling during England's defeat to Holland in the UEFA Nations League last summer.
The pair are set to line up against each other when City face Port Vale in the FA Cup third round at the Etihad Stadium on Saturday.
Ahead of the game, Guardiola said Pope's message was "not nice" but did add that Stones still had something to prove if he wanted to be considered one of the best in the world. The 25-year-old has been plagued by injury problems this season, only managing to start eight of City's 30 games.
"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 on Friday. "It's difficult to reach the potential that he has, he has to be at the level to play regularly.
"The last three seasons and a half he could not do it."
Stones has won two Premier League titles since moving to City from Everton in 2016 but only in his first season at the club was he able to make more than 40 appearances in a single campaign.
Guardiola was at a loss to explain the lengthy list of injures but hinted the defender problems were mental as well as physical.
"It's difficult to know the reason why," Guardiola said. "Sometimes when you have a tough injury, for example like Aymeric [Laporte] had this season or [Ilkay] Gundogan in the first season, sometimes it's unlucky, or [Benjamin] Mendy the year he arrived, first year he arrived.
"That can happen, you know, it's unlucky. But in the case of John I don't know. I don't know why he is not able -- we are not able -- to be a regular for a long, long period because he's a young player.
"He's still young. As a player he has his future in front of him, it depends on him. It's in his hands and in his head to become one of the best."
Port Vale are set to bring 8,000 fans to the Etihad for the tie against City, who have not lost a domestic cup tie since February 2018. The League Two side will be spearheaded by Pope, who scored a hat trick in a 3-1 win over Cheltenham in the last round, and all eyes will be on his battle with Stones.
After England's 3-1 defeat to Holland in the Nations League in June, 34-year-old Pope tweeted: "Just watched the highlights of the England game! I know I'm a League Two player, I know he plays for England, I know he's on £150k a week, I know he's a million times better player than me but I'd love to play against John Stones every week! I'd get 40 a season!"
The post was followed by hashtags "soft" and "weakaspiss". But when the draw was made, Pope, who has scored six goals in 26 games this season, back-tracked before branding Stones "the best centre-back in the world."
He wrote: "This tweet was six months ago and you've all managed to dig it up. In them six months he's improved dramatically and I think he's the best centre-half in the world."