Rio Ferdinand believes Manchester United are "the right club" for John Stones and has urged the Everton defender to reject a possible move to Chelsea.
Premier League champions Chelsea have made no secret of their desire to capture England international Stones - despite Everton boss Roberto Martinez insisting the 21-year-old will not be leaving Goodison Park.
Former United defender Ferdinand believes Stones would be "a lunatic" to join Chelsea, given the defensive options already available to Jose Mourinho.
Speaking at a BT Sport media event, Ferdinand is quoted as saying: "If he [Stones] goes to Man United, he plays every week so that's the right club for him.
"If he goes to Chelsea, he's not playing every week. If you say to any young footballer to leave a club to sit on the bench, you've got to be a lunatic. You have to be."
Regardless of whether Stones moves to Old Trafford, Ferdinand believes it is imperative United manager Louis van Gaal fields a settled back four in his second season at the helm.
"I don't think [Van Gaal] knows his best defence - that's a problem in itself," added Ferdinand.
"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.
"I played with [Nemanja] Vidic for six years with no fitness problems between us. I woke up on a Saturday knowing that Vida was going to be fit and he was the same with me. At the moment these guys aren't doing that.
"They don't know if Chris Smalling is going to be fit, if Phil Jones, Jonny Evans or Marcos Rojo are going to be fit. So how can you start to build relationships? That's been part of the problem for Van Gaal."
United have been linked with a move for Real Madrid's Sergio Ramos, although the Spain international now appears set to remain at the Santiago Bernabeu.
"I always knew that was never a goer," said Ferdinand. "I said at the beginning on Twitter that he's obviously up for a new contract [at Real] and he may be using United in that respect.
"Whether that's true or not I don't know but he's signing a new deal according to what we read."
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