LONDON -- Anthony Joshua dismissed Joseph Parker calling him "king of steroids" and resisted the temptation to launch a verbal attack on his rival champion.
Joshua will face New Zealander Parker in a world heavyweight title unification clash at the Principality Stadium in Cardiff, Wales, on March 31.
WBO titleholder Parker (24-0, 18 KOs), 26, told a New Zealand radio programme, "I call him [Joshua] the king of steroids."
Parker added: "I am not accusing him of using steroids, but I am saying it is a possibility."
IBF-WBF champion Joshua (20-0, 20 KOs), 28, insists he is regularly drug tested and was prepared to hit back with some trash talk of his own.
"I sign up three months in advance every time and I have to give them two slots in the day where I definitely will be, so they are able to drug test me," Joshua told reporters during his London news conference Tuesday.
"It used to happen to [Wladimir] Klitschko a lot. When I used to watch him, they used to disrespect him a lot of the time about his style and performance. They used to say other things about him.
"I think he was just a phenomenal fighter. I won't take it to heart. You just roll with the punches. People talk. When I am sitting at home with my family it is all irrelevant. It is only relevant when I am in front of the person; they didn't say it to my face, so I don't take it to heart.
"I didn't know how to take them; they talk a lot. That's why I asked for a coffee on the table because I was ready to start chatting a lot of s--- and get into some trash talking. I was ready for it.
"I even went to bed early for this. I was like, 'Let's get down to some trash talk.' In terms of the stuff they have been saying to me, I was ready to bounce it back, but it wasn't like that.
"I didn't know how to take the [Parker] camp, but they were respectful and I'm going to keep the respect and ambassadorial side of the sport. Hopefully after we can shake hands and move forward."
Joshua's promoter, Eddie Hearn, says the world heavyweight No. 1 is regularly tested by anti-doping agencies.
"I think he [Parker] regrets that, he has apologised on his Facebook page," Hearn told reporters, referring to Parker's comment. "People need to realise this is high-intensity stuff, a lot of pressure, and sometimes people say things that they shouldn't. Sometimes people say things for the hype.
"We pay something like £30,000 every fight to make sure the fighters are tested. As soon as the contract is signed, testing is under way -- that's WADA [World Anti-Doping Agency]. We optionally sign up for that.
"We are also with UKAD [UK Anti-Doping], through the BBB of C [British Boxing Board of Control], and that's 365-days-a-year, random whereabouts testing. The last three or four fights we have been tested eight times in camp by UKAD and WADA over a 12-week period. He is the one pushing for a clean sport."