Anthony Joshua's ability to take a punch was the chief talking point as he took the stage with fellow heavyweight champion Joseph Parker for the first time ahead of their unification fight.

A press conference featuring New Zealand WBO champion Parker and multiple belt- holder Joshua captured ample media attention at a London hotel on Tuesday as they contemplated their March 31 clash in Cardiff.

Joshua's height advantage was evident when the pair squared off for a stare-down but it didn't stop the team of Parker (24-0) continuing to taunt the Englishman (20-0).

Parker's promoter David Higgins brought up Joshua's "weak chin", a theme they had highlighted during fight negotiations.

Joshua says allegations he has been knocked out in training sessions were "fake news".

He had explanations for the three occasions he had been hurt or stopped in fights and regarded all of them as important experiences.

The most recent came in his compelling 11th-round defeat of Wladimir Klitschko in last year's title fight at Wembley in which he recovered from an earlier knock down.

"What I have learned from those adversities and storms, it will take more than any human to stop me from this journey," Joshua said.

"That's why I learned to not walk with sight, I walk with faith in this journey so in terms of you, using it as a PR stunt and the rumours you have heard, they are fake news."

Joshua said it was an honour to be on the stage with another world champion and he will be in peak physical condition to handle any tactics thrown at him by the smaller but quicker Parker.

"I don't know how to take his camp in terms of what's been said and what's been going on but I take everything with a pinch of salt and I roll with the punches."

An unbowed Parker acknowledged the fight would be the toughest of his career but is anticipating taking a clutch of world titles away with him.

He says the key will be his two-month build-up camp in Las Vegas with trainer Kevin Barry.

"I can't wait to put on a great performance, hopefully I will catch him on the chin and knock him out," he said.

"I've watched him for a long time. I know his strengths, he knows mine. I know his weaknesses and he thinks he knows my weaknesses."