It really is win or bust for Dillian Whyte and Joseph Parker at the O2 Arena in London tonight.

Both men have ambitions to be the heavyweight champions of the world, Parker for the second time having lost his WBO title to Anthony Joshua in April.

Joshua is the only fighter to have beaten the pair of them too, as he recorded a brutal knockout of Whyte in December 2015.

The winner of the bout tonight will most likely get a shot at a world title, but the loser realistically has nowhere to go, as losing to a contender rather than a champion doesn't do their aspirations much good.

What makes the fight even more interesting is that it genuinely a 50-50; they each have certain qualities that will really test the other, and it is sure to be a fascinating watch.

Tony Bellew and David Haye have delivered two bouts of that ilk on box office themselves, with the former stopping his opponent twice, at the same venue as Whyte meets Parker tonight.

They clearly know their boxing too, having both been world champions, but given their differences in the past is hardly surprising that they didn't see eye-to-eye when asked for their opinions on tonight's fight.

Bellew is in Whyte's corner, while Haye favours the chances of the New Zealander.

Haye believes that if Parker can measure the early pressure of the 'Body Snatcher', then he could potentially do serious damage late on, either by forcing a stoppage or on points.

"I see Joseph Parker potentially having problems with Dillian Whyte's jab for the first five or six rounds, but if Parker can stay disciplined and can keep educated pressure on Whyte, I believe Parker's engine is superior," he said.

"With Parker, I've seen in the past, he has fought at a lot higher pace. He's a younger guy, he's the more naturally-gifted athlete. AJ wasn't able to take him out. He's got the youth. As far as I'm aware, he hasn't been knocked out in sparring, or in a fight, or knocked down.

"If it gets rough, if it gets tough, my money goes on the guy who's got the bigger punch, and the better chin. I would put my money on Parker via points decision or a late stoppage."

However, Bellew sees it going the other way via Whyte on points, as he's shown in recent bouts that he has progressed a lot.

"I was solid on Whyte all the way through the week and I have changed my mind at the last minute in the past," he started. "But I am sticking with Whyte, although I think he might have to get off the floor.

"He is not getting through this without getting nailed hard and everybody is overlooking Parker's punching power.

"But Dillian has a lot going for him, he is vastly improved and seems to be thinking about the attacks these days.

"No, he's not in with a big, dozy, brute like Lucas Browne this time and Parker has wins against the better fighters, but I am sticking to Whyte on points."

If the professionals are so split, how are the fans supposed to work out who's going to win this one?

It's sure to be a cracking fight though, and one that could propel the victor one step closer to world glory.