Everton defender John Stones should join Manchester United instead of Chelsea, according to former Red Devils defender Rio Ferdinand.
The Toffees have rejected at least one £20m bid from Chelsea for 21-year-old England international Stones, with United also thought to be interested.
"If he goes to Chelsea, he's not playing every week," said Ferdinand.
"If you tell any young footballer to leave a club to sit on the bench, you've got to be a lunatic."
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Since joining Everton from Barnsley in 2013, Stones has made 44 Premier League appearances and earned four England caps.
Toffees boss Roberto Martinez has said he is determined to keep hold of the centre-half.
Ferdinand added: "He's at that stage of his development where he wants to play every week.
"If he goes to Manchester United, he plays every week so that's the right club for him."
Ferdinand, who played 453 times for United, believes Old Trafford boss Louis van Gaal needs defensive improvements.
United have Chris Smalling, Phil Jones, Marcos Rojo, Jonny Evans, Paddy McNair and Tyler Blackett as central-defensive options, while Daley Blind also played there during pre-season.
"I don't think Van Gaal knows his best defence - that's a problem in itself," said 36-year-old Ferdinand, who retired at the end of last season.
"Part of the reason he doesn't know it is because he hasn't had a chance to watch them all play over a long time - consistently for 12 or 15 games.
"If you don't get that familiarity between you as defenders, it's difficult to build foundations."