Anthony Joshua and Joseph Parker have shed the pounds for their world heavyweight unification title fight on Saturday.

At a weigh-in on Friday where both fighters showed respect for each other, WBA, IBO and IBF titleholder Joshua tipped the scales at 242 pounds (110kg) - 12 pounds lighter than for his most recent fight against Carlos Takam in October.

After the stare-down, Parker and Joshua shook hands and briefly chatted on the stage.

Renowned for his power punching having knocked out all 20 of the opponents in his professional career, Joshua said fans might see a different side to him on Saturday.

The fighters were addressing a crowd of about 4,000 people at the weigh-in at Motorpoint Arena in a rainy Cardiff.

A New Zealander with Samoan heritage, Parker entered the stage to a few jeers, moments after supporters welcomed him with a New Zealand haka and a Samoan siva.

Parker looked like he meant business, whereas Joshua was all smiles as he high-fived some fans on his walk to the stage.

Around 78,000 fans are expected at the nearby Principality Stadium for the fight between two unbeaten world champions.

Parker's amateur rival, heavyweight Junior Fa, who's been used by Joshua as a sparring partner in the past, is giving Parker the edge to win.

"Combinations you know .. a fast combination puncher is always hard to deal with. Anthony Joshua is a very great counter puncher. One punch. Parker doesn't do that you know. Parker likes to throw his punches in bunches which is very hard to counter off," Fa told Newshub.

"I can see this going four ways. I can see both of them knocking each other out and both winning by points. But I'm favouring Joseph Parker. We have seen Joshua fade in the later rounds. If Parker can put on a good pace, keep Joshua running for the first few rounds, which will get his legs tired, then mid-rounds get him stuck in the mud. Land a big punch and land a few combinations that will drop him."