Deontay Wilder says Anthony Joshua should listen to public demand and make the "best fight in the world".
The WBC heavyweight champion will defend his title against Luis Ortiz in the early hours of Sunday morning, live on Sky Sports, and sent another message to Joshua at the final press conference in New York.
Kell Brook, Deontay Wilder, Scott Quigg and Dillian Whyte in four fabulous weeks of boxing, live on Sky Sports.
Promoter Eddie Hearn insists Joshua is happy to fight Wilder next, if he wins a unification clash with Joseph Parker on March 31, live on Sky Sports Box Office, and the American says the bout should be made while both champions are in their prime.
Wilder, who plans to watch Joshua from ringside, told Sky Sports: "After I beat Luis Ortiz, this will solidify myself at the top of the division, and after this, if Joshua gets past Parker, there ain't no more excuses. There ain't no more time.
Let's make the best fight in the world happen right now, and the people want it.
"I want to fight while we're young, I want to fight while we're undefeated. I want to fight while we're healthy because after this, we don't know what can happen.
"Let's make the best fight in the world happen right now, and the people want it. The people want it right now. I want it, I can't wait, so come Saturday night I'm going to show and prove to the world who the hell I am."
But Wilder firstly needs to overcome Ortiz, a Cuban southpaw with an unbeaten record, and 'King Kong' promised to start his own reign as WBC champion.
Ortiz said: "Deontay is scared. He's talking a lot of nonsense. He's worried about what I'm going to do. This is my time. I'm going to show everyone.
I looked into his eyes and I knew that I'm not going to lose this opportunity.
"I'm 100 percent ready to go. Sparring has been amazing and I'm totally prepared for Deontay Wilder. Deontay's biggest mistake is that he talks too much.
"I looked into his eyes and I knew that I'm not going to lose this opportunity. I'm going to be the first Cuban and the first Latino born outside the country to win a title. Saturday night will be historic.
"The public gave me this opportunity to fight for the title and beat you for your belt. I'm going to make the most of my chance and knock Deontay Wilder out."
Watch Deontay Wilder vs Luis Ortiz live from Brooklyn, New York, in the early hours of Sunday morning, on Sky Sports Main Event, from 2am.