WBC champion Deontay Wilder's trainer and co-manager, Jay Deas, is giving IBF, IBO, WBA heavyweight champion Anthony Joshua (20-0, 20 KOs) the edge in his upcoming contest with WBO champion Joseph Parker (24-0, 18 KOs).

The two world champions are scheduled to collide on March 31 at the Principality Stadium in Cardiff, Wales. Sky Sports Box Office and Showtime will carry the fight.

Wilder (39-0, 38 KOs) will be waiting in the wings for the winner.

Wilder will first defend his title against undefeated Cuban puncher Luis Ortiz on March 3.

Deas expects a close contest in the first six rounds, but then expects one of the two to pull away. He gives Joshua the advantage to win the fight, but he doesn't give him a tremendous edge.

"I think it will be a very close fight after the first six rounds and Joshua will either then find a reserve and pick it up and pull it out, or Joseph will continue to the momentum into the later part of the fight," Deas told Brendan Telfer on RadioLIVE.

"I would have to say that Joshua has the advantage, just because of all the external things, but If Parker can handle all those external factors then it becomes an even fight. But I have to give Joshua a slight advantage in what will be a tremendous fight."

And what are those external things? Deas explains.

"The 5000 interview requests, the 100,00 people watching, the waiting in the dressing room for five hours before the fight," Deas said.

"On top of that, the 100-yard walk to the ring, the waiting while five national anthems are played, waiting under the video screen for 15 minutes - all these things that nobody thinks about, these are the things that Joseph has to overcome.

"The stuff inside the ring, he's fine. I think if you put him and Joshua in the ring where nobody is around, it's an even fight, but when you add all the extra stuff, you have to see if Joseph Parker is comfortable in that surrounding. He has travelled to England before and done well, so that is going to help, but this is a whole new animal, a whole new environment  and a whole new scale, so we have to see if he's up to the challenge."