Wayne Rooney has said it would be "disappointing" for Manchester United to lose "special talent" JJ Gabriel.
Gabriel, 15, asked to leave United and Barcelona and Real Madrid are among the clubs monitoring his situation, sources told ESPN.
He turns 16 next month and recently shone on his UEFA Youth League debut against Sabah by scoring a hat trick.
"I have seen JJ grow up, he has been in [my son] Kai's team," Wayne Rooney told Stick To Football on Disney+. "Anyone close to it knew that was coming.
"In fairness to Manchester United they have done everything, absolutely everything, to keep him at the club.
"The club have treated him probably differently to the other players because he is such a special player. I know, I recognise that, because I was that player at Everton. I was getting that treatment at Everton.
"As a club, you need to do [it] to try to keep the better players.
"It's disappointing because he is such a top player and a lovely kid.
"You never know whether it's gone too far or whether there is a chance for him to stay."
United believe they could rectify the issue, sources previously told ESPN.
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Rooney became the Premier League's youngest goalscorer when he struck for Everton aged 16 years and 360 days old in 2002. That record is now held by Arsenal's Max Dowman after he scored against Everton in March aged 16 years and 73 days.
Rooney became a United and England legend and now sees an exciting talent within Gabriel.
"He is a top player," Rooney said of the 15-year-old. "His ability, his balance, he has shown he can go up the ages and score goals. The next step is first-team football where it's different, and you never know until you're in there.
"But he's such a special talent who understands the game really well.
"At some point this season he would [have] made his debut for the first-team, I'd imagine, so that's where it's disappointing."