British challenger David Haye insists he will be the first fighter to knock out WBA heavyweight champion Nikolai Valuev in Germany on Saturday (Sunday AEDT).

The brash Londoner has only a handful of heavyweight fights under his belt since stepping up from cruiserweight, but insists he will put the 2.13m Russian, who tips the scales at around 145kg, on the canvas at the Nuremberg Arena.

Having described Valuev as a 'circus freak', Haye has taken every opportunity to trash-talk the champion, but the Russian insists he will use the British challenger's words as motivation.

Valuev laboured to a majority decision win over Evander Holyfield in his last bout in December 2008 and is regarded as a safety-first fighter.

Haye is a hard-puncher with 21 knockouts from 22 fights, the vast majority of which were at cruiserweight, but Saturday's fight will be a huge test of both his stamina and strength in dealing with a heavier and taller opponent.

But with typical bravado, Haye insists he will be Valuev's worst nightmare having already dreamed about putting the Russian on the canvas.

"He hasn't fought anyone of my calibre - he's never fought anyone in their prime or someone so fired up," said the 29-year-old.

"I'm not one of these guys he's used to fighting. I'm not over the hill, I'm not tainted, I'm not past my sell-by-date. I'm fresh, I'm ready."

Haye has a point. Valuev has fought just four times since the only defeat of his career to Ruslan Chagaev in April 2007.

All of his opponents - Holyfield, John Ruiz of the USA, Belarusian Sergey Lyakhovich and Canadian Jean-Francois Bergeron - took him the full twelve rounds and his last knockout win was against Monte Barrett in October 2006.

But having regained his WBA title this summer after Chagaev was stripped of his belt, Valuev inists he is in no mood to relinquish his title.

"His comments have been very motivating," said the 36-year-old.

"But let's see what Haye has to offer inside the ring. I don't think he will be able to follow it up. But I will not under-estimate him."

This is Haye's first shot at a world heavyweight title after moving up a weight division and is a step into the unknown against Valuev who is 23cm taller and nearly 40kg heavier.

The British fighter has been sparring with his trainer wearing 15cm-high boots to prepare for the height disadvantage he will face.

But Valuev's manager Wilfried Sauerland has posed key questions about Haye's confidence which the Brit will need to back up with some impressive boxing.

"I don't know where he (Haye) gets his confidence from," said Sauerland.

"He is untested at heavyweight and got knocked down a lot of times in his career.

"Now he is facing a proven champion with 50 victories, so I really wonder why he is so optimistic."