Ray Wilkins believes Wayne Rooney will have a better chance of winning trophies if he stays with Manchester United rather than joining Chelsea, and has urged the England striker to embrace the "healthy" competition for places at Old Trafford.
United have confirmed they rejected a second bid from Chelsea for Rooney, whose future remains shrouded in doubt.
Former Red Devils manager alex Ferguson last season claimed the 27-year-old wanted to leave, and Rooney is understood to have been unimpressed by quotes from new United boss David Moyes this summer that suggested he would effectively have to be an understudy to main frontman Robin van Persie.
Wilkins, who played for both clubs and has also coached at Chelsea, said: "It shouldn't end this way, it's getting horrible.
"Once you leave Manchester United there's only one way you're going.
"Man United are in the top three biggest clubs on the planet, therefore they will always buy and buy and buy because they always want to be successful.
"If you want to win things then there's no better club to be at than Manchester United.
"So what if you've got a bit of competition with Robin van Persie? It's healthy.
"He should stand up to the plate and show these people what he's made of. He's got so much wonderful football left in him."
United said on Monday that their position remained that Rooney was not for sale.
Wilkins feels that should that stance change, the Red Devils would be "crazy" to let the player switch to another English club - although he admits he would personally love to see Rooney sign for Chelsea.
The 56-year-old said: "If I was David Moyes there's no way I would sell him to anyone in England. I'm sorry - he'd have to go abroad.
"I would love him to join Chelsea, though. I would love nothing more than to see Wayne Rooney wearing that blue shirt.
"I just think he's ready for his second coming. He's 27 years old and if for some strange outcome he stays in England, then Wayne is ready to start again.
"Man United would be crazy to do that though, they shouldn't sell him to one of their closest rivals."
Rooney, who didn't travel with United to Sweden for last night's pre-season friendly against aIK due to a shoulder injury, was at the Barclays Premier League champions' Carrington training ground in Manchester yesterday.
Meanwhile, United defender Rio Ferdinand says he and his team-mates constantly gossip about transfer speculation "like fellas sitting in a pub".
The 34-year-old, who will play in his testimonial match at Old Trafford on Friday, insists he and his colleagues are no different from football fans generally when it comes to the summer silly season of comings and goings.
"We come in and look at the papers or social media or whatever and say 'so and so has bought so and so, what do you think, what do you think, is he any good? I don't think he'll be any good, he'll be a great big waste of money'," he said.
"We're just exactly the same, it's just like four fellas sitting in a pub. We're just sitting in a training ground
doing it (instead). People don't expect it because we're players."
Ferdinand has been impressed with how new boss David Moyes has resisted the temptation to change too much of what is clearly a winning formula.
He said: "The manager knows I've got a certain way that I need to train, that I know my body - like Giggsy (Ryan Giggs) as well. He has kind of left it open to us to continue what we were doing to get us (playing) last season.
"That's been fantastic for me because you get worried a little bit and think 'oh, it's a new manager, is he going to let us continue our regimes that we're involved in to get us out to play football and to train every day?'
"But it's the sign of a great manager that he has (let that continue)."
Ferdinand feels Moyes has also struck the right balance in his relationship with the players.
"The new manager is quick to join in the banter but when it's work time, it's work time," he said.
"The players aren't there to mess about on the training pitch, we're there to enjoy ourselves but to be drilled and to make sure we're all going in the same direction."