The 19-year-old is yet to start a Premier League fixture, but he is pushing for a first-team place at Goodison Park.
The England U21 international joined Everton from Barnsley in January.
Martinez told the Liverpool Echo: “I think he can develop here fighting for his place.
“He’s earned that and I don’t think he needs to go out on loan and play. Here he is learning on a daily basis from Jags (Phil Jagielka) and (Sylvain) Distin, and that’s exactly what he needs.
“He’s not the same player from pre-season, he’s already gone to a different level.
“He’s got an incredible future which we’re all excited about and we’re looking forward to him fighting to see how quickly he can get in the team.
“Every player is an individual and needs different things.
“John has had first-team experience. He played enough with Barnsley in the Championship to know what to expect.”
What is your opinion? Feel free to discuss the article under. You have to comment by using your Facebook profile. Be fair and have respect for other people and opinions!
The start of the 2017-18 Premier League season is just around the corner and is shaping up to be one of the most competitive yet.
As always it is the so called “big clubs” that have splashed the most cash in the transfer window so far this summer. Manchester United or City? Arsenal or Tottenham? Who are the winners and losers of the transfer window so far?