Ashley Young believes under-fire Manchester United team-mate Luke Shaw can be "one of the best in the world" if he works hard and keeps his head down.
The 22-year-old left-back has endured his fair share of ups and downs since joining from Southampton in 2014, fresh from becoming the youngest player to feature at the World Cup in Brazil.
Shaw is facing a battle to go to this summer's tournament after being left out of Gareth Southgate's latest squad, which versatile left-back Young has taken his place in after becoming first choice under Jose Mourinho.
The United manager has endured an uneasy relationship with the 22-year-old, who the Portuguese criticised having hauled him off at half-time of Saturday's FA Cup quarter-final against Brighton.
Young was not keen to get into the whys and wherefores but has seen enough of Shaw to back him for the very top.
"I am not here to talk about other people and whatnot," he said.
"Obviously he is a player that wants to do well, I want to see him doing well. It's like all players, you just have to get your head down and work."
Asked if Shaw has it in him to come again, Young added: "Yeah, of course. He is a fantastic player. I feel he can be one of the best in the world. As I say, you've just got to work hard."
Young and Shaw appear to have a good relationship off the field despite vying for the same starting berth, with the winger-cum-full-back crediting that competition as helping him to kick on at 32.
"Of course, everybody in the squad pushes each other on," Young said.
"We've got a healthy competition in our squad and when you've got world-class players training day in, day out, everybody wants to be in that team.
"Everybody wants to be in that starting XI.
"It is tough. I've always said, when you join a club like United it's a tough place to play at.
"But if you play and you train there and give 100 per cent, then get your opportunity and I've always said you always get your opportunity there."
Young's resurgent form at United saw him return to the England set-up in November, having last played for his country in September 2013.
The 32-year-old returned off the bench against Brazil and now has a chance to rubber-stamp his place in the squad ahead of the World Cup, with friendlies against Holland and Italy over the coming week.
"I feel like I am playing with confidence, I have done all season," Young said. "I've been playing more than I thought I would.
"It's obviously credit to the manager (Mourinho). He's put me in the team and I've stayed there.
"I've wanted to cement my place in the team and, like you say, I am back in the England squad, which I am delighted to be in.
"There's a World Cup at the end of it. Who knows what's going to happen? I've just got to be impressive to the England manager and hopefully be on that plane.
"I've just got to keep playing as well as I can, and I'll just have to wait and see."
Young hopes his versatility will help earn a squad place and said: "I think now in modern-day football you've got to play in different positions."