The ink was barely dry on his Manchester City contract when the question was posed: where do Everton find the next John Stones?

Ashley Williams arrived from Swansea and Lamine Kone is courted at Sunderland but their strengths are leadership and aggression. The simple fact is Ronald Koeman believes he may have the answer right in front of him.

Mason Holgate is a tall, stylish ball-playing defender that Everton signed as a teenager from Barnsley for £2million after barely 20 first team games. Sound familiar? He can play right back or centre back and has such insouciant temperament that Koeman thought nothing of asking him to mark Zlatan Ibrahimovic during Wayne Rooney's testimonial at Old Trafford last week.

Mason Holgate followed the same path to Goodison Park as John Stones

Holgate was tasked with marking Zlatan Ibrahimovic during Wayne Rooney's testimonial

'You have to understand that he is 19 years old but maybe he showed more confidence than some other players on the pitch,' purred Koeman afterwards. 'He’s a big talent.'

Everton players will testify, earning Koeman's praise does not come easy and Holgate is not taking his first team graduation for granted.

'The manager has been great to me and not just because he put me in the team!' Holgate says.

'Before I went out at United, he just said it doesn't matter whether you are 19 or 36, I'm putting you in because you are ready and you are good enough. Don't have any fear, just show what you can do.

'I know I have to work to impress him, I wouldn't expect anything else but it's nice to know I could get a chance this season if I keep at it. The United game was a great experience.'

Ronald Koeman has seen Stones depart, but has brought in Ashley Williams from Swansea

It is hoped that Holgate can also fill the void left by the £47.5m man

And how was Zlatan?

'It's just how big he is. That's what hits you,' says Holgate. 'I think he's down as 6ft 5ins tall but whoever was counting must have just given up. He seems taller. I went to head the ball at one point and his foot was next to my head. It must have been 6ft 4ins in the air and he wasn't even jumping.

'He didn't speak to me really he was just talking to his teammates and for me it was about trying to make sure my body was in the right position all the time to make sure he didn't score. I marked Anthony Martial later. His change of pace is just effortless so both were a really good test.'

The 19-year-old talks well. Team-mates joke he is rarely seen without close pal Everton left-back Brendan Galloway, who is considering a loan move to Newcastle. Holgate is bright, polite and firmly grounded. He lives on his own, near Warrington, but confesses sheepishly that he still takes his dirty washing back to mum Julie at the family home near Doncaster.

Close pal Brendan Galloway grapples with Chelsea's Diego Costa

Holgate is grounded and is realistic about the season ahead at Goodison Park

Indeed, Holgate has no delusions about following in John Stones's career path though it's easy to understand why Koeman has high hopes.

'The comparisons are there with John because of the background,' says Holgate modestly. 'He was a few years older than me at Barnsley so we never crossed paths there, though he helped me when I came to Everton. All the senior players have. I started out in midfield so I've always tried to be composed on the ball but I've certainly worked harder on my defending since I've come here.

'I'm still growing. I'm 6ft 3ins tall now and starting to fill out so I'm handling the physical side and the likes of Phil Jagielka or David Unsworth, the U21s coach, are always around to give me advice.

'John's a great footballer so comparisons are really nice but I've been reading Rio Ferdinand's autobiography lately and I suppose if anything I'd like to play the way he did.'

Stones is now a Manchester City player and Everton must plan accordingly

Holgate, 19, says he is still growing and will look to mark his mark this season

Coincidentally, Holgate had a taste of life at Manchester United when he was invited to train there last year prior to his Everton move.

'I was with the younger players such as Marcus Rashford but it still opened my eyes to the step up that was required at that level. The pace and intensity. It took me a day or so to adjust but I think I held my own in the end.'

Ultimately, United hesitated over making an offer allowing Bournemouth to step in and agree a fee with Barnsley. Holgate was on the motorway at Birmingham, en route to the south coast, when Everton intervened.

'It all happened very quickly but I'm happy I made the right choice. I just want to play now. Once you get a taste for the first team you just want more.'