Tyson Fury v Wladimir Klitschko: Can 'Gypsy Warrior' stun champion?

How do you measure madness? Well, Tyson Fury is a decent yardstick. One minute he's Batman, the next he's Bette Midler, the next he's a turbulent priest. But beating Wladimir Klitschko on Saturday would be his maddest deed of all.

Almost nobody in the know in Dusseldorf thinks the Englishman will do it. Wrest the world heavyweight championship from a man who hasn't lost in 11 years, has had 27 world title fights and made 23 successful title defences? It makes no real sense. But neither does Fury, by his own admission.

"Not everyone is as gifted as me in being able to talk rubbish," Fury once told me. Which explains why an awful lot of British fans want Fury to lose. There is no wave of red, white and blue rising behind Fury, as there was with dear old Frank Bruno or, to a lesser extent, Lennox Lewis. Because British fans prefer their boxers to be nice as pie and humble, rather than wilfully controversial.

"Jesus tells me to love my fellow human beings," says Fury. But sometimes it doesn't seem that way. Not when he's comparing homosexuality to paedophiles or threatening to hurt a pesky journalist. Which is a shame, because the 'other' Tyson Fury is intelligent, engaging and actually quite likeable.

Fury has appeared relaxed all week, but other than his serenading of Klitschko at Wednesday's public workout he has been unusually staid. Perhaps the sight of Klitschko taking 45 minutes to wrap his hands - for what was a brief move around the ring - brought home the seriousness of what he was about to embark upon. And Klitschko doesn't really talk rubbish, in any of his four languages.

At Friday's weigh-in - held in the nearby city of Essen and not open to the public, you suspect to keep Fury's supporters at bay - the Englishman suddenly seemed alone and anxious. But for the 39-year-old Klitschko, it was business as usual.

"Sometimes in training camp I wake up and wonder who I'm fighting," says the Ukrainian, who turned pro after winning a gold medal at the 1996 Olympics and whose second reign has lasted nine years. "The faces are the same, everything is the same, and I have to look at the poster to see who it is this time."

The quality of Klitschko's opposition is often lampooned but he has fought pretty much everybody out there, compiling a record of 64 wins, with 53 knockouts, and three defeats. In contrast, Fury has fought almost nobody of note.

A reluctant Tyson Fury shakes Wladimir Klitschko's hand at the weigh-in

Fury was impressive in beating fellow Briton and former world title contender Dereck Chisora last November. But the 27-year-old was booed out of the ring after beating Kevin Johnson in 2012, floored by the obscure Neven Pajkic in 2011 and again by career cruiserweight Steve Cunningham in 2013.

But Fury's team are convinced Klitschko is showing signs of degradation. And they might be right. In his last fight, the game but unheralded American Bryant Jennings employed clever lateral movement to break up the champion's rhythm. Klitschko won by a wide unanimous decision but looked ordinary at times.

"Most of Klitschko's opponents are beaten before they turn up," says Fury. "All they're looking for is a few extra dollars for their pension fund. They give it a go for a couple of rounds and then look for the floor. If they don't do that, they look to make it through all 12 rounds, just so they can lose on points.

"But I'm one of those athletes who has a miracle growth when I'm shoved in front of a big crowd. I'm not one to lie down."

While Fury has height, reach and a narrow weight advantage over Klitschko, he is also mobile and a decent boxer. As such, the idea that Fury - the self-proclaimed 'Gypsy Warrior' - will take it to Klitschko from the opening bell might prove to be false. Peter Fury, Tyson's trainer, is a calculating presence in his nephew's corner and unlikely to instruct his man to stand and trade.

But Fury will have to engage at some point and he will do so in the knowledge that Klitschko, for all his might, has not - and cannot - put muscles on his chin.

Having been knocked out three times - by journeyman Ross Puritty in 1998, the marauding Corrie Sanders in 2003 and Lamon Brewster in 2004 - Klitschko learned to fight in a more cautious manner. But Kubrat Pulev wobbled him with a jab only two fights ago, as did Mariusz Wach with a huge right hand in 2012.

"In heavyweight boxing, when both men have dynamite in both hands, either one of them can go down with one punch," says Fury, who is challenging for Klitschko's WBA, IBF and WBO belts at the 50,000-capacity Esprit Arena.

"That's why everybody loves the heavyweights. It's not the fact it will happen, it's the fact it could happen at any given moment."

However, while Fury is a decent boxer who hits hard enough, the suspicion is that Klitschko is a better boxer who hits even harder. True, Fury jumped straight back up after being nailed by Pajkic and Cunningham. But people tend not to jump straight back up after being nailed by Klitschko, they tend to go to sleep.

How Fury reacts if he does lose has been a topic of conversation all week. He has hinted in the past that he has fits of mental turmoil - "you'll just get me in different moods," he told me in 2013, "you might see a flashy, arrogant person, you might see someone who can't be bothered living any more" - to the extent that even the idea of winning doesn't seem to thrill him much.

"It takes me about 10 days to get back to reality again after a fight," Fury told BBC Sport this week. "After such a high, you've got to have a crash. It will be all over the papers on Sunday and Monday. But after that, it's chip paper.

"But if people do forget about me after two minutes, better to have had a two-minute heyday and be forgotten about than never to have had a heyday at all."

If he makes mad things happen on Saturday, Fury will be everywhere for weeks. Some big bombs landed, a couple of knockdowns, maybe even a victory. It's happened before, it will happen again, so keep your eyes on Dusseldorf.

Listen to commentary of the Klitschko v Fury fight live on BBC Radio 5 live from 21:30 GMT on Saturday, 28 November, with live text commentary on the BBC Sport website, mobile and app.