Anthony Joshua has sold 300,000 tickets in his last four fights, an astounding average of 75,000 per fight. On Saturday, in front of what is expected to be at least 80,000 at Wembley Stadium in London, Joshua will defend his IBF-WBA-WBO heavyweight titles against Russian Alexander Povetkin in a battle of former Olympic super heavyweight gold medalists.

Joshua is 21-0 with 20 knockouts and is regarded as boxing’s biggest star, figuratively as well as literally.

The best, though, could be yet to come. Trainer Rob McCracken raves about Joshua’s progress but said there is a long way to go. Joshua won the 2012 Olympic super heavyweight gold medal with only 40 fights and precious little big-time amateur experience.

And even though he’s the unified champion, McCracken said Joshua isn’t yet a finished product.

“He’s improving and learning all the time and this is a fight that is going to get him a step closer to his peak, but he’s not there yet by any means,” McCracken told Yahoo Sports. “This is a good learning fight for him. It’s a good fight and a good opponent for A.J. It will be a real test, but I think after Povetkin, he should be near to becoming the finished star he has the ability to be.

“He’s getting more experienced. He makes better decisions in the ring, but he still has to learn about, say, when to punch and when not to. It’s important to punch at the right time. It’s one thing to throw 20 punches, but if you miss 10, you’re exposing yourself to being hit. He needs to get better at determining when to punch so like in this fight, Povetkin is not in a position to go back at him.”

Joshua is being used as something of a marketing tool in the fight. The card will make the debut of the streaming service DAZN (pronounced duh-ZONE) in the U.S. For $9.99 a month, DAZN will have a significant amount of combat sports content on it.

It’s a gamble, at least the way promoters in the U.S. see it. Yahoo Sports spoke to more than six promoters, all of whom say DAZN’s business model is flawed and the numbers don’t add up. It faces heavy competition for the fight fan’s money, giving that the new ESPN+ charges $4.99 a month, UFC Fight Pass is $9.99 monthly and boxing and UFC pay-per-views are in addition to that.

Hearn, though, believes there is a room for everyone and says he believes DAZN and ESPN+ at a combined $15 a month “is a no brainer” for boxing fans.

Starting with a title defense by Joshua is clearly a way to try to get fans to give DAZN a shot.

“It’s huge for DAZN [to have Joshua headlining its first event in the U.S.] because I believe Anthony is the biggest star in world boxing so to carry him on your platform and launch your platform with him is huge,” Hearn said. “The issue for DAZN at the moment in terms of marketplaces is we are starting from scratch. So when you’re talking to fighters and those same fighters have other promoters or their managers and advisers in their ear trying to push them away from DAZN, it’s up to us at DAZN to build credibility in the marketplace with a fighter like Anthony Joshua.

“We’ve got Anthony Joshua, the unified heavyweight champion and the biggest star in world boxing on DAZN. You have the undisputed cruiserweight champion who fights on DAZN, Aleksandr Usyk. We have four or five other world champions signed up and there are more to come.”

Hearn, though, isn’t trying to pit it as a battle between DAZN and ESPN+. ESPN has a vastly greater brand recognition in the U.S., and announced Thursday that it has passed 1 million subscribers for ESPN+.

DAZN only opened up for sign-ups this week and there is no telling how many U.S. fans will be able to see the Joshua-Povetkin fight, but by the normal standards, it’s going to be very low.

But Hearn said it will take time to build it out.

“You shouldn’t look at this as DAZN versus ESPN+,” Hearn said. “For $15 a month, you get 16 of their U.S. shows, 16 of our big U.K. shows, you’ve got three weight classes in the World Boxing Super Series, you’ve got all of Bellator, you’ve got all of Combate Americas. And DAZN is not just a boxing platform. It’s just the first piece of content they’ve purchased.

“Over the next months and years, they’ll have everything. But I will say this about DAZN in relation to ESPN+ when it comes to boxing: On DAZN, you won’t have a situation where the best fights are not on the app or not on the platform. A lot of ESPN+’s content is diluted. I have seen some of their fight nights and it is not, in my opinion, of a consistent level like DAZN will be. Don’t get me wrong: They’ll have some big names on there, etc., etc., but their standard stuff versus our standard stuff won’t be as strong.”

Hearn could use a big performance by Joshua on Saturday to generate excitement and raise DAZN’s profile.

Joshua is a heavy favorite over the 39-year-old Povetkin, who is 34-1 but whose best days appear behind him. At the Westgate Las Vegas sports book, Joshua is minus-1400 while Povetkin is plus-800.

Yet, Joshua knows it’s not going to be easy. He’s carrying a heavy burden. Asked how much pressure he feels going into the fight, Joshua was blunt.

“Loads of pressure; tons of pressure,” he said. “That’s the reality of it. Even though we present ourselves as calm, cool and collected, underneath all that, we both know what we’re in for. But it’s not only this fight with Povetkin, it’s been every fight and every future fight I’ll be in. They all come with the same pressure, so I just try to roll with the punches. What more can I do except give it my best?

“That’s what I’m going to do Saturday night. … I’ll find a way to win and grind it out.”

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