England forward Raheem Sterling is “one of the most talented players in the world”, according to team-mate Daniel Sturridge.
Sterling, 21, was heavily criticised for his performances as England reached the last 16 at Euro 2016.
“It is just a matter of time before you see him take his game to the next level and I am sure that will be very soon,” Sturridge told BBC Radio 5 live.
England are preparing to face Iceland in Nice on Monday (20:00 BST).
Manchester City winger Sterling missed chances in both matches and was dropped for the final group game against Slovakia, which ended 0-0.
“Raheem is one of the strongest; he has got thick skin,” Liverpool striker Sturridge told 5 live’s senior football reporter Ian Dennis.
“He doesn’t worry too much about what people say. He has to worry about his game and that is it. That is all he ever does.
“He works so hard on the training field and is one of the most talented players in the world.
“We look at players playing for so many different countries but you can’t name many 21-year-olds who have played as many first-team games at the highest level as Raheem has.”
Sterling left Liverpool to join Manchester City in July 2015, his £49m fee making him the second most expensive British player of all time.
In his debut season at the Etihad Stadium, he scored 11 goals in 47 appearances, winning the League Cup.
“I feel the criticism he has received has been harsh because he is 21,” said Sturridge.
“He has performed at the highest level for the last few years and has played for big clubs.
“In the games he has played for England, he has not performed as badly as people have made out – he has done quite well.”
New City boss Pep Guardiola has spoken to Sterling, telling him he would fight for him as long as he was committed to the club.
Sturridge added: “We have to groom him, nurture him and help him become one of the best players in the world.
“I believe he can, because he has all the tools for it. You are still finding yourself and you are not a grown man at 21.
“Just let him continue and he will come good. That is fact because he does have the ability.
“It is important for people to understand he will come good and he will show everyone what he is about. I am sure of that and I can’t wait to see it happen.”