What is it?A battle between Goliath and, well, Goliath - the only David-like figure in the ring at Color Line Arena in Hamburg on Saturday night will be the referee.

Why's that?Ukrainian heavyweight champion of the world, Wladimir "The Steel Hammer" Klitschko is just a shade under two metres tall (just over 6ft 6in). His opponent on Saturday night, American Tony "The Tiger" Thompson (who can blame a breakfast cereal for ruining what should be a tough-sounding nickname) is, by comparison, a paltry 6ft 5in.

Of course, they're not the tallest heavyweights - that accolade falls to Russian Nikolay Valuev. Three years ago the 7ft, 23st (147kg) colossus - who is now, by the way, an aspiring actor - beat American John "The Quiet Man" Ruiz in Berlin.

So what do I need to know?Considering the 17st 2lb Thompson is the latest fighter charged with resurrecting America's heavyweight tradition, he has big shoes to fill. Or, of course, he can just borrow someone else's.

The 36-year-old is probably best known for beating Timor Ibragimov in February of last year. Thompson's boxing shoes were stolen before the fight and he had to borrow basketball shoes from a Fox Sports Network producer (who managed to milk the situation by sitting in the front row at the fight and waving his bare feet at the TV cameras).

He'll be up against a far better fighter this weekend (the bout is live on Setanta Sports 1).

A month after that fight, Klitschko - who has been training with Ireland's Andy Lee in Austria, who is preparing for his fight in Limerick next week - defeated Ray Austin in Germany with a second-round knockout. The 17st 5lb boxer didn't use his right hand even once during the fight, instead alternating between left jabs and left hooks. A few months later, Lamon Brewster - who had knocked out Klitschko in 2004 - threw in the towel in the sixth round against the Ukrainian, who had decided he needed both hands (the American fighter not quite living up to his nickname "Relentless").

Afterwards, Klitschko revealed he had broken a finger on his left hand early in the bout.

Klitschko defeated Sultan Ibragimov at Madison Square last February to unify the IBF, WBO and WBO heavyweight titles (despite many boxing reports referring to them as cousins, Sultan is actually no relation of Timor).

But Klitschko won't be simply able to stand off Thompson and beat him with jabs alone, as Thompson has a long reach himself and his southpaw stance will cause the champion problems.

So who'll win?Klitschko is hot favourite to maintain his status as the undisputed heavyweight champion of the world. But we reckon Thompson has unrivalled motivation for winning the bout.

In his blog detailing the day he left for Florida to start his training for his "dream fight", Thompson wrote: "I left the wife and seven kids back at home with the broken air conditioner, broken dishwasher, broken dryer and the electricity down in one half of the house. To me, this is God's sign that I better get this fight done."

Thompson may not be afraid of Klitschko, but he may well be afraid of going home having lost.