In less than three weeks, Anthony Joshua will defend his world title against former longtime champion Wladimir Klitschko in one the biggest heavyweight fights in years.

Wembley Stadium in London, where the fight will take place April 29, sold out quickly and will have a British boxing-record crowd of some 90,000 on hand. The fight will generate tens of millions of dollars from the gate, the Sky Box Office pay-per-view in the United Kingdom (where Joshua is a bona fide star) and German network RTL (where Klitschko has a lucrative deal) -- not to mention dozens of other television networks from around the globe that will pay for the right to televise the fight.

There is another $3-million plus on the table from American networks Showtime and HBO, who, according to sources with knowledge of the situation, have already made deals with Joshua promoter Matchroom Boxing and Klitschko promoter K2 Promotions.

But it has been a difficult process because Showtime has a contract with Joshua and HBO has one with Klitschko and neither is willing, understandably, to give up its rights. So they had to figure out how to make it work because this is not a pay-per-view fight in the United States like Floyd Mayweather-Manny Pacquiao or Lennox Lewis-Mike Tyson, massive events that forced the networks to come together and meld their broadcast and production teams as well as their public relations efforts for the event.

So for the past few months, Showtime and HBO have been trying to work out a deal they can both live with that will assure U.S. television coverage. They’re not there quite yet, hence the reason why the American television plans have not been announced.

According to the sources, the networks have agreed to the most significant basic deal point, that Showtime will air the fight live in the late afternoon/early evening and HBO will present a tape-delay of the fight a few hours later in prime time. Showtime would pay more for the fight because it has the live airing and HBO would pay quite a bit less to show it on tape.

Heavyweight titleholder Anthony Joshua and Wladimir Klitschko have a two-fight deal. Sean Dempsey/EPA

But any disparity in the price each network would pay could even out in the long run because Joshua and Klitschko have a two-fight deal. So regardless of who wins the networks would flip positions for the contractual rematch, meaning HBO would have the right to air it live with Showtime getting the delay. Of course, there is no guarantee of a rematch, however, because if Klitschko loses, and he is the underdog, there is a good chance he could retire at age 41 after back-to-back defeats.

Also agreed to is that both networks will send their personnel to the stadium to put on their telecast rather than remain in the U.S. and call the fight from a studio. Both have already done site surveys of the stadium and are ready to go -- assuming the deal between the networks is finalized.

One source said the networks have already taken care of many issues with the promoters, such as credentials, broadcast positions and other production details, but they’re not there yet on everything because, as one source said, “there are games being played on both sides.”

One of the big issues is how the networks would announce a deal without giving the other a leg up. The idea discussed was for them to put out a joint press release. The hope from the promoters and networks was that they would have wrapped up the deal by this past Saturday so it could be announced early this week.

But HBO, according to one of the sources, said it wanted the announcement to come during its telecast of the Vasyl Lomachenko-Jason Sosa card on Saturday night. According to one source, Showtime Sports boss Stephen Espinoza said no to that scenario because “it would give HBO an advantage, so it wasn’t announced Saturday night.”

HBO has no more boxing events between now and April 29 on which to promote the fight. Showtime still has a “ShoBox” card on Friday night and a “Showtime Championship Boxing” event on April 22, but the fight is getting close, and there is precious little time remaining for either network to seriously promote such a big fight.

The view of one of the sources involved is that “there’s a lot of gamesmanship going on on the part of both networks. Who knows what they’re going to do or if they’re even willing to go with the deal they’ve negotiated at this point.”

Another small, but important detail to HBO, according to one of the sources, is what will take place during the roughly four-hour window between the end of Showtime’s live broadcast and HBO’s tape delay.

HBO wants assurances that Showtime will not release footage of the fight, publicize the result of the fight or do anything else to help spread the word on the outcome following its broadcast -- even though any legitimate fight fan will surely already know what happened.

In the end, the rival networks will surely make a deal -- there’s no way the promoters will allow it to fall apart with that much money at stake in rights payments -- but making the sausage has been brutal.

Naturally, neither network wanted to discuss the matter.

“We’re not going to comment on any ongoing negotiations,” Showtime spokesman Chris DeBlasio told ESPN on Monday.

Also Monday, HBO spokesman Ray Stallone told ESPN, “Nothing to report at this time."

There had better be something to report soon. The fight is 19 days away.