HOLLYWOOD -- For the cast and crew, filming Cinderella Man was no fairy tale experience.

Almost from the beginning of the shoot in Toronto last year, word was that Russell Crowe's notorious mood swings were unsettling.

Even director Ron Howard has admitted Crowe can be a difficult collaborator.

"Directing Russell is like shooting on a tropical island. The weather is going to change several times a day, but you're shooting there for a reason," says Howard.

"Sometimes those dark clouds are just what you need. And sometimes you wish it would stop raining so you can do the sunny scene."

Howard knew what to expect when he agreed to direct Crowe in Cinderella Man.

The two had worked together on A Beautiful Mind which garnered Howard Oscars for best picture and best director.

"Russell's reputation precedes him. Before we began work on A Beautiful Mind I called directors and producers who'd worked with him in the past.

"They all said he could be difficult, but they also all said the end result was worth it and that they'd work with him again in a minute. It's exactly how I feel."

Both Crowe and his co-star, Renee Zellweger, snubbed the Cinderella Man wrap party in Toronto that Howard and producer Brian Grazer threw, adding fuel to the rumours making the movie had not been the best of experiences for either of them.

Crew members and extras were less approving of Crowe's eccentricities than Howard, often talking to reporters, but insisting on anonymity.

A story that appeared in Britain's Daily Sport claimed Crowe was a diva putting his gym off limits and failing to turn up on set when he was needed.

The film set insider allegedly told The Daily Sport "Russell had his own private gym which no one was allowed to touch.

"He put drapes around his trailer to fence it off.

"He was also a no-show on set one day when he had a toothache. He gave no notice. He just didn't show. The entire crew showed up, but couldn't work."

Stories also appeared in Britain and Crowe's native Australia in which Zellweger reportedly said he had made life miserable for her.

During her press interviews for Bridget Jones's Diary: The Edge of Reason, Zellweger said working with Crowe on Cinderella Man was tougher than gaining and losing the weight to play Bridget a second time.

"Both movies were difficult for me and for different reasons," said Zellweger.

"Russell is a perfectionist. He's very demanding of himself and others. Yes, he gave me a hard time, but no harder than he gave anyone else."

The British and Australian press further reported that Crowe had made scenes uncomfortable for Zellweger because he refused to shower after his intense boxing scenes and then expected her to embrace him or kiss him.

"I was surprised and distressed to hear that I have made such disparaging comments about Russell," said Zellweger.

"Russell Crowe does not deserve to think these are the sort of things I have been saying. These are words someone else has put into my mouth."

Zellweger did not deny Cinderella Man was a tough shoot, but insisted "working with Russell is only tough because he raises the bar and that is a welcome challenge.

"It's wonderful to watch how uncompromising he is in terms of bringing a character to life."

One of the most bizarre stories to come from the Toronto set of Cinderella Man had Crowe, who plays a boxer, pulling a Mike Tyson.

He reportedly bit the ear of his friend and bodyguard Mark 'Spud' Carroll.

In an open letter to the Australian press who had made the original stories front-page news, Crowe admitted to a fight with Carroll, but said it was all a misunderstanding.

Crowe called the altercation "a little push-around one Friday night."

Carroll had apparently shared with Crowe some of the cast and crew members' perceptions of his behaviour.

"I thought he was accusing me specifically of something and I took offence to it. It doesn't surprise me that I'm overly sensitive to gossip and speculation and heartily sick of other people's 'perceptions.'

"Spud was passing on other people's 'perceptions' and I shot the messenger," said Crowe in his own defence.

Carroll also wrote an open letter to the Aussie press vehemently denying Crowe had bitten his ear.

"He did take a nip at my chest," said Carroll

"I was trying to smother him at the time, so I can understand the move. As for calling it a fight, believe me, we have done much more damage to each other playing touch football."