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)

Lukas Podolski of Koeln is challenged by Philipp Wollscheid of Nuernberg during the Bundesliga match between 1. FC Koeln and 1. FC Nuernberg at RheinEnergieStadion on April 3, 2011 in Cologne, Germany.

Mark Wagner, the collage artist, challenges viewers to examine their relationship with money and the capitalist society in which we live. Photo: “Way of the Dinosaur”, cut one-dollar bills. (Photo by Mark Wagner)

Children fall as they slide down on a float along a chute to cross a pool of water and foam during the “Letniy Gornoluzhnik” (Summer mountain puddle rider) festival at the Bobroviy Log Fun Park near the Siberian city of Krasnoyarsk, Russia, August 23, 2015. The annual competition marks the end of the summer season at the Siberian ski, rest and entertainment resort. (Photo by Ilya Naymushin/Reuters)

Model airplane enthusiasts take part in an event at a model airplane field in Mamak district of Ankara, Turkey on December 30, 2021. Model airplane enthusiasts, each owns different sizes and types of aircrafts, have the opportunity to have fun while training. Weekend meetups also give them an opportunity to help each other on technical issues. (Photo by Dogukan Keskinkilic/Anadolu Agency via Getty Images)

Rickshaw puller Shiori Yoshida, 28, attracts tourists to the guided tour at the Asakusa district in Tokyo, Japan on August 22, 2023. Pullers walk or run an average of 20 km (12 miles) a day and, in addition to being physically strong, they must have extensive knowledge of Tokyo and know how to engage with the tourists who mostly hire them for sightseeing. “I have fun and enjoy myself”, Yoshida said. “In order for the customers to enjoy themselves, I also enjoy myself”. (Photo by Issei Kato/Reuters)

West Bromwich Albion's Saido Berahino (front) is challenged by Manchester City's Fernandinho during their English Premier League soccer match at The Hawthorns in West Bromwich, central England December 4, 2013. (Photo by Eddie Keogh/Reuters)

Nice's Youcef Atal, left, and PSG's Juan Bernat challenge for the ball during the French League One soccer match between Paris Saint-Germain and Nice at the Parc des Princes stadium in Paris, France, Saturday, May 4, 2019. (Photo by Christophe Ena/AP Photo)