Ruud van Nistelrooy has revealed the most painful part of his Manchester United exile is missing out on Roy Keane's testimonial at Old Trafford tonight.

The Dutch striker is back in Holland training with Marco van Basten's World Cup squad after being kicked out of United's team hotel by Sir Alex Ferguson on Sunday.

As one of the few senior players who stood up for Keane over the infamous never-to-be-aired MUTV rant which led to the Irishman's abrupt departure from Old Trafford in November, Van Nistelrooy was looking forward to meeting up with his old team-mate again.

Instead, the 29-year-old is now back home, knowing his United future is non-existent, having phoned Keane to explain why he could not be there for the encounter with Celtic.

"It is painful because I wanted to be there to respect Roy but I have not been allowed to," Van Nistelrooy told Sky Sports. "That is the most painful thing of all. I have spoken to Roy and he is totally fine about it."

Van Nistelrooy is expected to be part of van Basten's World Cup squad, which is due to be announced on May 15th. And, given the severity of his falling-out with Ferguson, it appears he will be using the competition as a shop window to display his talents.

It is believed Ferguson has now spoken to Red Devils chief executive David Gill about the situation, as the Scot promised in the aftermath of Sunday's win over Charlton.

While United are refusing to state their exact position, it seems impossible to believe there is any other scenario than the player will be sold this summer.

However, with two years remaining on a £90,000-a-week contract, the deal will have to be one which appeals to the forward, who only last month became the eighth player in United history to score 150 goals for the club.

Meanwhile Keane insists he will not be rushed into making a decision about his future. After gaining the 'closure' he was looking for from his testimonial game at Old Trafford, the veteran midfielder will spend a short holiday with his family before meeting his surgeon and deciding whether he is fit enough to continue his career at Celtic for another season.

Hoops boss Gordon Strachan has left a one-year offer on the table for Keane to consider. But, while the 34-year-old claims he has made no definite decision about his short-term future, the indications are that he will call time on an illustrious career.

"I realise my heart could be telling me one thing and my body another but I am quite relaxed about the situation," said Keane. "I don't feel too bad but equally I do not feel as though I have done myself justice at Celtic.

"I have suffered one or two niggling injuries, which could have been influenced by the amount of travelling I have been doing and also a torn hamstring which I am certain came about because of my hip operation.

"Nothing is definite yet but if I am suffering niggling injuries all the time, that is no use to anyone."