Challenger Bulgarian heavyweight boxer Kubrat Pulev (R) lies in the ring after being knocked down by Ukrainian WBA, WBO, IBO and IBF heavyweight boxing world champion Vladimir Klitschko (L), who celebrates with his brother Vitali (2nd L), as referee Tony Weeks checks on him after their title fight in Hamburg, November 15, 2014. World heavyweight champion Vladimir Klitschko knocked out Bulgarian challenger Kubrat Pulev with a fierce left hook in the fifth round on Saturday to retain his IBF title and end his opponent's unbeaten record. (Photo by Fabian Bimmer/Reuters)

Alex Lual (R) in action against Trent Girdham (L) during the undercard bouts ahead of the WBO Asia Pacific Super Welterweight Title Bout between Tim Tszyu and Takeshi Inoue at Qudos Bank Arena, in Sydney, New South Wales, Australia, 17 November 2021. (Photo by Dan Himbrechts/EPA/EFE)

(L-R) Dustin Poirier punches Conor McGregor of Ireland in a lightweight fight during the UFC 257 event inside Etihad Arena on UFC Fight Island on January 23, 2021 in Abu Dhabi, United Arab Emirates. (Photo by Jeff Bottari/Zuffa LLC)

(L-R) Alex Pereira of Brazil punches Israel Adesanya of Nigeria in the UFC middleweight championship bout during the UFC 281 event at Madison Square Garden on November 12, 2022 in New York City. (Photo by Jeff Bottari/Zuffa LLC)

Boxers Deontay Wilder, left, and Tyson Fury exchange words as they face each other at a news conference in Los Angeles, Wednesday, November 28, 2018. The pair are slated to fight Saturday night for Wilder's WBC heavyweight title. (Photo by Andrew Couldridge/Action Images via Reuters)

Vitali Klitschko of Ukraine poses in front of Odlanier Solis of Cuba during the weigh in at Sport Karstadt on March 18, 2011 in Cologne, Germany. The WBC World Championship Heavyweight fight between Vitali Klitschko of Ukraine and Odlanier Solis of Cuba will be held on 19 March 2011.

Jake Paul (left) lands a punch to the face of Anderson Silva during a boxing match at Desert Diamond Arena in Glendale, Arizona on October 29, 2022. (Photo by Mark J. Rebilas/USA TODAY Sports)

In this Sunday, March 11, 2017 photo, children fight in a boxing ring in Chitungwiza, Zimbabwe. Zimbabwean boys as young as 10 hurry every weekend to a boxing ring whose nickname, Wafa Wafa, in the local Shona language suggests that whoever enters will be lucky to come out alive. (Photo by Tsvangirayi Mukwazhi/AP Photo)