Ronaldo became embroiled in the longest running transfer saga of the summer when he expressed a desire to leave Old Trafford for Real Madrid.

When he finally decided to stay where he was, Ronaldo claimed his initial feelings were based upon a belief that, having won the Champions League last May, he had reach the pinnacle.

However, in deciding to stay, the 23-year-old has merely opted to set himself new targets.

"I am an ambitious person, not just in football but in normal life," he told MUTV.

"I have an opportunity to be better than I am and I am always keen to get better. I am still young and I have won things already.

"But it is not enough. I want to win more. I am at the right club and I am playing with the right players."

The most obvious area to improve is the goals scored column.

Ronaldo accepts exceeding last term's incredible tally of 42 will not be easy.

But he got his fourth of the campaign against West Brom on Saturday and the race is on to do even better.

"I hope to score more goals," he said. "It will be hard to score 42 goals again but I believe in myself, my colleagues and Manchester United.

"It is going to be tough but I train the same and I am the same person.

"I am feeling better now and this is the challenge for me."

Meanwhile, United boss Sir Alex Ferguson has tipped Ronaldo to be crowned world player of the year in December - but revealed he could leave his star man out of Tuesday night's Champions League clash with Celtic.

Given United were crowned kings of England and Europe last May, Ronaldo is odds-on favourite to land the FIFA world prize and the prestigious Ballon D'Or, for which he headed the list of nominated players released over the weekend.

Ferguson cannot see any justifiable reasons why both honours should not come Ronaldo's way.

However, the Red Devils chief feels Ronaldo has not quite recovered from the ankle operation he had in the summer.

And after a conversation with former assistant and current Portugal boss Carlos Queiroz, given the swift turnaround,

Ferguson is tempted to let Nani loose on Celtic instead.

The Scot explained: "Cristiano will win both player of the year awards, I am sure of it. If he doesn't, I want to sign the guy who does.

"But Carlos feels Cristiano is still finding it hard to recover from a Saturday game to a Wednesday.

"I need to look at this game and the fact it is on a Tuesday and assess whether to bring in Nani."

"Cristiano is coming on terrific now. He was magnificent on the Saturday against Sweden but when Portugal played Albania last Wednesday he was a bit flat.

"It is simply because of the recovery thing."

As Nani also scored at the weekend, and is far fresher, the option is an attractive one, although Ronaldo's class is a major counterweight.

"Nani only played for 36 minutes for Portugal and 15 for us on Saturday so he is nice and fresh," he said.

"When you get so many games in a row after an operation like that, the adrenalin helps you out once but then it dips.

"But the thing about Ronaldo is that with one flick he can score because he is such a talent in the box."

While Ferguson's dilemma will probably not be resolved until an hour before kick-off, he does not intend to spend any time worrying about Ronaldo's subdued reaction to the 95th goal of his United career.

His response has been viewed in some quarters as an indicator Ronaldo wished his dream move to Real Madrid had gone through this summer.

Ferguson, who persuaded him to stay, is not getting involved.

"I read that stuff," he said. "I am not even going to answer it."