The two best heavyweights in the world, unified titleholder Anthony Joshua and titlist Deontay Wilder, have their schedules in perfect alignment.

Anthony Joshua-Carlos Takam Where: Principality Stadium in Cardiff, Wales

When: Saturday

TV: Showtime, 5 p.m. ET

They will each defend their belts in mandatory fights on back-to-back weekends, both televised on Showtime. But the ultimate goal isn't for them to fight on consecutive weekends; it is for them to fight each other.

Joshua and Wilder, both big men with charisma and massive punching power, continue to talk about an eventual showdown. Their summit meeting appears inevitable. It is the biggest fight in the division -- by far -- and perhaps the biggest fight in boxing.

"I think he's what the division needs, and I think this is what Wilder needs, so we'll give it to them," Joshua said. "I say it's definitely a potential for 2018. What else am I going to do in 2018?"

Said Wilder: "The ultimate goal is to get Joshua."

But first they have business to attend to, and if they are successful in their upcoming fights, there will, of course, be the difficult matter of negotiations. Those talks will be a fight unto their own, almost as rough as what might go on between the ropes.

Anthony Joshua, left, defends his heavyweight belts against late replacement Carlos Takam on Saturday. Stephen McCarthy/Getty Images

But first up, Joshua (19-0, 19 KOs), 28, of England, will make his fourth title defense when he faces late replacement Carlos Takam (35-3-1, 27 KOs), 36, a Cameroon native living in France. Takam was on standby in case something happened to mandatory challenger Kubrat Pulev. Indeed, Pulev suffered a shoulder injury two weeks ago and was forced to withdraw from the fight, and Takam, who had been training, was pressed into service to challenge Joshua on Saturday (Showtime, 5 p.m. ET) before an expected crowd of about 75,000 at Principality Stadium in Cardiff, Wales.

One week later, on Nov. 4 (Showtime, 9 p.m. ET), at Barclays Center in Brooklyn, New York, Wilder will defend his belt against mandatory challenger and former titleholder Bermane Stiverne, the man Wilder easily outpointed to win the belt in 2015.

The Las Vegas-based Stiverne (25-2-1, 21 KOs), who turns 39 on Nov. 1, had been training for a fight on the undercard after making a deal to step aside in order to allow Wilder an optional defense against dangerous contender Luis "King Kong" Ortiz. But after Ortiz tested positive for two banned substances last month and was dumped from the fight, Stiverne was tapped to take his place.

Wilder (38-0, 37 KOs), 32, of Tuscaloosa, Alabama, has made five defenses but does not have nearly as significant a victory on his resume as Joshua recorded in his last bout. That was an 11th-round knockout of former longtime world champion Wladimir Klitschko in an epic fight on April 29 before a British boxing record crowd of 90,000 at Wembley Stadium in London. In the leading fight of the year candidate, Joshua retained one belt and won a vacant one.

"I'll fight Wilder next year and make it a priority, 100 percent. There's no doubt about that." Anthony Joshua

After the fight, most thought Klitschko would exercise his contractual right to a rematch. Joshua promoter Eddie Hearn of Matchroom Boxing was already in talks to bring the fight to T-Mobile Arena in Las Vegas for what would have been Joshua's American debut. But Klitschko elected to retire, so it made far more financial sense for Joshua's fight with Pulev -- and now Takam -- to take place in the United Kingdom, where Joshua is like a rock star.

Joshua and Hearn say they have plans to have him fight in the United States. That is where a potential unification showdown with Wilder is likely to take place on pay-per-view.

"I think so," Joshua said of facing Wilder in America. "I can see it happening in the U.S. If you came to Wembley on April 29, you saw what that was like. It was phenomenal. That was really good. So, do we want to create that again or should we go overseas and do something new? It's good to have options."

Anthony Joshua, right, defeated Wladimir Klitschko in April 2017 in the biggest win of his career so far. Richard Heathcote/Getty Images

Joshua is by far the biggest boxing star in the U.K. but would like to follow in the footsteps of Britain's all-time best heavyweight champion, Hall of Famer Lennox Lewis, which means also making a name for himself in the United States.

"I would love to fight the great champions that the United States has produced. At the same time, I'll fight anywhere. I'm fine staying in the U.K., but America's definitely at the top of the pyramid, for sure," Joshua said. "The thing is, before, I wanted to go out there for the experience, but now I want to go out there and make me some money. For what fight, that's what's going to be interesting. ... I think [a Wilder fight] could be built to be something just like the Klitschko fight. It should be better."

Hearn wants to bring Joshua to America, but for a big fight. That's what a Klitschko rematch would have been, and it's what a Wilder fight will be.

"I just want to prove to the world that I am the best. That's all I want to do. I don't care about who's the A side, who's the B side, where the fight's going to be. I don't care about that stuff, just me in the ring." Deontay Wilder

"It's definitely on the radar. If you want to try and change the game and break down boundaries, that includes America, Africa and the Middle East as well," Hearn said. "It's hard to leave the U.K. with 75,000 to 90,000 people compared to what the U.S. is. But Anthony Joshua is a global brand. He's not British heavyweight champion; he's a world heavyweight champion. The key now is to get the win [Saturday], and then in the weeks that follow, put our plans together for 2018, and hopefully America is included in that."

Though Wilder is training for Stiverne, he said he plans to watch Joshua fight Saturday.

"Well, of course I'm going to look at it. I definitely look at the guys at the top of the division," Wilder said. "Anybody say they don't watch, then they're lying. Of course I'm going to look and see what's going on and see how this person did against this person, and so forth and so on."

Heavyweight titleholder Deontay Wilder, right, stopped Bermane Stiverne in Round 1 in the rematch. AP Photo/John Locher

Wilder very much wants to unify titles and face Joshua. He's not convinced that Joshua feels the same way, however.

"Joshua say he need more time; he ain't ready. He wants to put himself in a better position. But you already fought a guy [Klitschko] that got way more experience than I," Wilder said. "I don't understand this sport when it comes to me. It feels like I'm better off not being in this sport than being in it. I don't understand it. All this stuff has just been a buildup for me. But I can handle it well, though. I can handle it so well, and I can't wait. All this needs to be released. Unfortunately for Bermane Stiverne, come Nov. 4, it will be released."

And then, Wilder hopes, the fight with Joshua will be on deck. With victories -- and they are both huge favorites -- they will be unencumbered by mandatory defenses. It's certainly possible they could each have another fight first, but by the end of 2018 their fight should have marinated long enough.

"I just want to prove to the world that I am the best. That's all I want to do," Wilder said. "I don't care about who's the A side, who's the B side, where the fight's going to be. I don't care about that stuff, just me in the ring."

Joshua is unimpressed by Wilder's list of opponents thus far, but he knows their fight is the big one and what fans want to see. He said he is willing.

"Where I'm coming from is that in a career, it's all good going undefeated and looking good, but when it's all said and done, how are people going to remember you? [Wilder] hasn't had any memorable fights," Joshua said. "He needs a real remarkable fight to stamp his name in the history books of heavyweight boxing. He needs that more right now, especially being in America. This is the Mecca of boxing. I even need it. I need Wilder to have a remarkable fight. I need to be the one that steps up to make this dream a reality. I would be honored to go out there and compete with Wilder.

"I'll fight Wilder next year and make it a priority, 100 percent. There's no doubt about that."