Boxing: US commentator James Smith rates Anthony Joshua ahead of Joseph Parker

Anthony Joshua (L) and Dillian Whyte in action during Sunday's British and Commonwealth heavyweight title fight. Photo/Getty.

American boxing commentator James Smith rates British champion Anthony Joshua as the most impressive up-and-coming heavyweight, and says Kiwi prospect Joseph Parker needs to step up his development and fight better quality opponents.

Joshua defeated former kick-boxer Dillian Whyte to take the British heavyweight title with a bruising seventh-round knockout on Sunday.

Smith believes the 26-year-old possesses all the qualities to take him to the top of the division and says he is capable of beating new world champion Tyson Fury and former champion Wladimir Klitschko.

"I think he'd be fine. He might win," Smith told Radio Sport.

"I'm really interested in Anthony Joshua. He is the best of the guys looking up, the guys coming up in the heavyweight ranks.

"Right now he would be the number one up-and-coming heavyweight in the world, in my opinion."

Smith also likes what he sees in Parker, and while understanding of his gradual progression through his undefeated 17 fight career (15 knockouts), believes the time is right to start pitting him against more evenly matched opponents.

"Parker's right in there but he's a few years younger. I think he's three years younger than even Joshua," he said.

"At 23, you take your time with him but step up the competition, fight different type of styles, but get some guys that have a little bit more speed and power and can actually hit him back.

"You have to step him up against a guy who has the ability to compete with him, and speed and size are what they need to match Joseph up (with).

"I'm sure that's what we'll see in the coming months with him. I'd be very excited about the prospects for Joseph Parker."

Parker's next fight is against experienced 31-year-old American southpaw Jason Bergman (25, 11, 2) at the Rumble in Paradise in Samoa on January 23.