A leaner and lighter Anthony Joshua weighed in some six pounds heavier than Joseph Parker on Friday for the battle of the undefeated heavyweight world champions in Cardiff.

Joshua, the reigning WBA, IBF and IBO world champion, is also taller and with a six inch reach advantage over Parker, who will be bringing his WBO belt to the Principality Stadium for Saturday night's unification fight.

"I've been running well, training well," said the 2012 Olympic champion, who has a 20-0 record with all his fights won by knockout. "Losing that little bit of extra weight has made things that little bit easier. I feel better...if everything goes to plan, you'll see I'll be a lot sharper and my reactions and timing will be a lot better."

Joshua's camp had made much of just how seriously the 28-year-old was taking training, his obsession with shedding the pounds and how that had been paying off in his ringcraft and training.

Parker, 24-0, took it as a compliment ahead of what will be the biggest fight of his career, with an 80,000-strong crowd expected through the doors on Saturday.

Joshua believes that he will only get better as time goes on. He does not consider himself to be at the prime of his career.

“You’re going to see me start priming, but I’m not in my prime yet,” Joshua added. “When you see someone in your prime is when they stay at the top for four or five years, when you see someone getting to their prime, that’s what you’ll start seeing now.

“It’s him being humble, and not trying to be too over-confident (when he says he is yet to decide how to win).

“In my head I have to prepare for a 12-round fight, but if we’re talking about where it’ll end, I’m hoping to go somewhere between seven and nine.”