Anthony Joshua vs Joseph Parker press conference
A win for Joseph Parker could set up a trilogy, according to Eddie Hearn Getty

Anthony Joshua's promoter Eddie Hearn believes a win for Joseph Parker would not only set up a potential trilogy but also make the New Zealander an overnight global star.

Joshua (20-0) will put his WBA, IBF and IBO titles on the line while Parker (25-0) will put his WBO title on the line when the two unbeaten heavyweights meet in their title unification clash in Cardiff on 31 March.

The winner of the bout will not only hold four titles but will also be one win away against WBC heavyweight champion Deontay Wilder from becoming the first heavyweight to hold all four major titles.

Joshua is the betting favourite heading into the contest as many see him as the one making history. However, that will only make an unlikely win for Parker even bigger as it would send shock waves across the boxing world, according to Hearn.

"The biggest fight in world boxing would be the rematch [if Parker beats Joshua]," Hearn told RadioLIVE's Sunday Sport via Newshub.co.nz.

"If Parker can win the fight but it opens up so many doors for Parker, Deontay Wilder, Tyson Fury, whoever, but right now this is the biggest heavyweight fight out there and who knows there could be a Joshua vs Parker I, II, III, who knows.

"I don't think anybody is looking past this fight, from any camp, so if Parker is to win he becomes a huge star and we are in the business of working with huge stars, but Anthony Joshua is our guy and for me, there is only one winner of March 31."

If Joshua loses, he can exercise a rematch clause but that is not the case for Parker if he suffers his first professional loss.

Hearn adds that the fight is dangerous for "AJ" for this sole reason as Parker will not only hold four titles and become a star if he wins, but also has the added motivation of being able to help his family become financially secure.

"I said in the build-up to this fight this is another reason why it's so dangerous - Anthony Joshua, in my opinion, is the biggest star in world boxing and if Parker beats him he becomes the biggest star in world boxing," Hearn explained.

"Because he would be holding four of the heavyweight belts and he would have just beaten the man. Trust me when I say when you see the spectacle on March 31 and the platform, the production and atmosphere - all these things will turn Joseph Parker into a star if he can dethrone Joshua.

"That in itself is a risk and that in itself is a worry to us, because we know what Joseph Parker is fighting for - he is fighting to change his life. The fight itself and the money itself will change his life forever. He is setting up a legacy and making his family for generally financially secure. But I also get the impression that is not why he is here - he is here to compete and win and to become the man."

Regardless of the dangers that come with the title unification fight, Hearn is confident Joshua can get the job done and extend his record to 21-0.

"This fight can end in the first round or the twelfth round, but my prediction remains the same, I believe Anthony Joshua will be victorious on March 31," Hearn added.