Former WBC heavyweight champion Vitali Klitschko believes his younger brother, Wladimir Klitschko, had the best performance of his long career last Saturday night at Wembley Stadium in London.

Klitschko suffered his second consecutive defeat, when he was stopped in eleven rounds before a record crowd of 90,000 fans.

With the victory, Joshua became a superstar by raising his undefeated record to 19-0 and all 19 by knockout. He unified the IBF, IBO, WBA heavyweight belts with the win.

Klitschko was down and nearly out in the fifth round, but he recovered and then came back to drop Joshua in the sixth and nearly finished off the 27-year-old boxer.

In the championship rounds, Joshua got a second wind, rallied with two more knockdowns before the referee stopped the contest in the eleventh.

Vitali who is now the Mayor of Kiev, was very proud of his brother's performance in the contest.

There is an immediate rematch clause, but Wladimir has yet to reveal if he intends to go in that direction. Joshua is planning to fight again in the fall, on a date between September and December.

Some are calling for Wladimir to retire, but Vitali feels his brother is still young enough to continue his career. Going into the fight with Joshua, Klitschko had been inactive since November 2015, when he suffered an upset decision loss to Tyson Fury. That was Klitschko's first defeat in over ten years.

"I am very proud of my brother," Vital Klitschko told Bild-Zeitung. "That was his best fight. Unfortunately, the result was wrong. He is not too old at the age of 41. He was very quick on his feet, he was great. I even found him better than Joshua who is 14 years younger. No matter how Wladimir decides how he plans his future as a sportsman - I will support him with all his strength," Vitali said.