Dereck Chisora lit the touchpaper ahead of his WBC heavyweight title challenge by slapping champion Vitali Klitschko at Friday's weigh-in in Munich. The eccentric Londoner is a rank outsider ahead of the weekend's bout and attempted to get under the long-reigning champion's skin.

After weighing in at 241 - just a pound oheavier than his lightest weight for a professional bout - Chisora butted heads before slapping Klitschko's face hard.

The two men were pulled apart, with a furious-looking Klitschko, who had weighed in three pounds heavier, left with a red mark on the left side of his face.

Chisora's camp said they were unaware of the stunt beforehand, with trainer Don Charles even branding the slap "unacceptable".

Meanwhile, Chisora aims to put two recent defeats behind him and "shock the world" by snatching the WBC title.

Despite being a relative novice, Chisora, 28, has already seen two clashes with Klitschko's brother Wladimir scuppered by the Ukrainian's injury withdrawals.

He was scheduled to fight the 35-year-old for the IBF and WBO belts in December 2010 before a stomach injury forced the champion to pull out and the rescheduled bout in April last year also fell through with Klitschko blaming a problematic rehabilitation.

While Wladimir went on to beat David Haye instead, Chisora remained at domestic level and lost his British and Commonwealth titles to Tyson Fury. Though he went some way to redeeming himself with a career-best performance against Finnish star Robert Helenius before Christmas, a controversial split decision ultimately saw him suffer a second career defeat.

The Zimbabwe-born Briton therefore takes on long-reigning heavyweight king Klitschko as a huge outsider, with some bookmakers pricing him as generously as 10/1 to dethrone the champion in his adopted homeland.

"I'm the underdog in this fight which is exactly how I like it because when I knock him out in the eighth round it will shock the world," said Chisora, who has a record of 15-2 (9KOs) and is ranked 14th by the WBC.

"I know I've got to go in there and do a job on him. I'm in tip-top condition and the best shape I've been in in my entire career, so I'm confident I'm going to smash Mr Vitali Klitschko to bits.

"I'm going to war with him. I'll make sure that he won't get to use his big height and reach advantage against me with the way I'm going to fight him and I've got the eighth round in my head that I'm going to stop him in.

"He won't be able to keep up with the pace I'm going to set. It will be at 100mph and his old legs won't be able to keep up. I'm not scared of him. He's human, he bleeds and so do I.

"I promise you, it's the end for Vitali. I will end the Klitschko reign and cause a massive upset that will be felt around the world.

"Everyone else who has fought the Klitschko brothers has been scared. This is one cat that isn't scared of him - or anyone - and I'll throw him off of that throne he's been sitting on for the last few years."

Klitschko has spent the build-up to the fight talking up Chisora's credentials, citing his performance against Helenius in Finland in December as proof of his credentials.

"He's the strongest challenger out there and I always want to prove myself against the best," insisted the 40-year-old (43-2, 40KOs) this week.

"He is young, wild, aggressive and hungry. He marches forward all the time. The fight will be interesting."

Chisora has a reputation for mind games but Klitschko has found little to get wound up about.

"All I know about Chisora is his professional career," he said. "He has a good chin and good boxing quality.

"We make small talk and he's been friendly. It's nothing personal; just business. That's why I smile at him.

Chisora is joined on the Olympiahalle bill by countryman Stephen Smith, as the featherweight returns from his shock British and Commonwealth title defeat by Lee Selby against Arpad Vass.