IBF, IBO, WBA, WBO heavyweight world champion Anthony Joshua is targeting the winner of the rematch between Tyson Fury and Deontay Wilder - and says a full unification fight "has to happen in 2020" as he targets all four major belts.

Joshua won back his four titles from Andy Ruiz in Saudi Arabia last week, avenging his shock defeat at Madison Square Garden six months earlier. Ruiz has dropped Joshua four times to secure a seventh round stoppage.

The one belt outside of Joshua's collection is the WBC title, which Wilder has held since 2015.

Wilder is due to face Fury in a rematch on February 22. According to Joshua, he wants to fight the winner in an undisputed bout with five titles at stake.

Wilder and Fury fought to a controversial twelve round split draw in December of 2018.

"I feel like it's 'The Lord of the Rings', the last ring, let's get it on, let's make history," Joshua told BBC Radio 2.

"It has to happen in 2020, we're in the same division, same era, if these guys want to make history - especially Wilder, because he has the last belt.

"We created history by becoming a two-time champion of the world, and I feel like we can add to that legacy in 2020."

Whether or not that can happen is up for debate.

In the last few days, the IBF and WBO have ordered Joshua to make mandatory defenses.

The WBO's mandatory challenger is Oleksandr Usyk,  who earlier this year moved up to heavyweight after becoming an undisputed champion at cruiserweight. And the other is IBF mandatory Kubrat Pulev.

And Joshua has no plans to avoid either man.

"If I don't fight those guys, I'll have to give up my belt, and I'd rather fight to defend them," Joshua added.