Bernard Hopkins says boxing is in "fantastic shape" following Anthony Joshua's thrilling victory over Wladimir Klitschko and believes "the sky is the limit" for the undefeated Briton.

Joshua and Klitschko produced one of the best heavyweight fights in recent memory in front of a 90,000 crowd at Wembley Stadium last Saturday.

Having knocked down Klitschko in the fifth round, Joshua recovered after being sent to the canvas in the sixth, producing an 11th-round barrage that resulted in two more knockdowns before the referee called a halt to proceedings.

Joshua is now 19-0, his triumph adding the WBA and IBO titles to his IBF belt he successfully defended.

And, speaking ahead of Saturday's catch-weight bout between Canelo Alvarez and Julio Cesar Chavez Jr, former middleweight and light heavyweight champion Hopkins was full of praise for Joshua and his impact on boxing.

"When was the last time, other than a football stadium, other than a soccer stadium, 90,000 people packed an arena to watch a heavyweight breakthrough? Ninety-thousand people came not to eat popcorn and hot dogs, they watched a fight and they watched a breakthrough, the changing of the guard," Hopkins told Omnisport.

"And you can't knock Klitschko because he fought one of the best fights I've seen him fight in a long time. I didn't think Joshua was going to get up and trust me, Klitschko would tell you that too if you asked him.

"Boxing is not in good shape, it's in fantastic shape, because the head to the body is attached now. It's called the heavyweight division. It's always been the division that the world's been captivated by because of the history – Ali, Mike Tyson, George Foreman, [Evander] Holyfield, on and on and on and on."

Asked how big Joshua can be, Hopkins replied: "Bigger than his right hand that he throws, bigger than his heart and chin that he showed and displayed in getting nailed and getting off the corner and getting off the ring. When you look at that, the sky is the limit.

"The heavyweight division is always about your longevity because I don't know a heavyweight in any era that didn't have a chance of knocking you out in one punch. There are small heavyweights, there are big heavyweights, but they are heavyweights, they're 230, 215 [pounds].

"But Joshua's not only athletic, not only has skills ... when you're athletic, you've got skills and you've got the chin to take the biggest punch like that, it shows that he can take a punch and get up and restructure his mind and his body and his soul and come back. Klitschko was like, 'did he get up?'.

"When you look at Joshua, I was excited that he won, even though I picked Klitschko because of age. I'll go for the old dog with the cane and the teeth that he can take out his mouth and put them in a jar at night. I just thought that Klitschko, last hurrah, not ready to leave, is going to come with his A-plus game and he did."