CARDIFF, Wales -- Anthony Joshua called on Deontay Wilder to face him this year after his points win over Joseph Parker on Saturday.
The WBA-IBF-WBO champion challenged Wilder to start talks for a bout to decide the undisputed world heavyweight champion.
It is the biggest fight waiting to be made in boxing and would be the first four-belt world heavyweight title fight.
Joshua (21-0, 20 KOs) triumphed by scores of 118-110, 118-110 and 119-109 and attention immediately turned to WBC titleholder Wilder (40-0, 39 KOs).
"2018 was always the time to capture all the belts and we are one away now," Joshua said in a news conference.
"I'm not in the business of hype, hype, hype, talk, talk, talk. I think me and Eddie [Hearn] have to go to America to see what the situation is. We have to sit down behind closed doors and see how serious they are.
"It's the same thing always [with Wilder]. I have all the belts here. Why do I have all these belts, just to give someone a bonus."
Joshua's promoter, Eddie Hearn, says a unification fight with Wilder needs to happen in 2018 but does not think the American deserves a 50-50 split.
"I think it has to happen in 2018," Hearn said. "It's just a case of whether it happens next. If they stepped up and were actually serious about the fight, it could happen next. But with them they are so erratic, you just don't know.
"Wilder fight has to happen this year because at some point we will have to drop a belt and the whole point of the [Wilder] fight was to unify all the belts. We have to sit down in the next two weeks and see if there's that fight in the summer."
Joshua, 28, declined to condemn Wilder for his "I want a body on my record" comment but did say: "Wilder is Wilder, that's what you're going to get. I always say a prayer in the corner for success and that my opponent is safe."
The Briton captured Parker's WBO title but had to go to points for the first time as a professional in a fight that lacked his usual explosive finish.
Parker (24-1, 18 KOs), 26, was gracious in defeat -- the first of his professional career -- but eager to fight Joshua again.
"I want to do it again," Parker told a news conference. "I thought my movements and the body shots [were good]. There are a few things I have to work on and I look forward to a rematch."
Parker's promoter, David Higgins, is confident the New Zealander will be back in big fights soon.
"Joseph is now a big name and I'm certain he will fight Anthony Joshua again in the next year or less," Higgins said.
Parker's trainer, Kevin Barry, was critical of Italian referee Giuseppe Quartarone's interruptions. Joshua had a 6-inch reach advantage and Barry said his fighter was not allowed to fight up close when he got the chance.
"It was very important for us when we did close the distance that we were able to work the inside," Barry said. "I tried to speak to him, but he had no idea of the question I asked him.
"But we were beaten by a better and bigger man. I was impressed by some of the things he did. He held his hands a lot better than he has in other fights and he was hard to hit."