A referee tries to separate two cocks fighting during a Cock fighting tournament on December 3, 2016 on the outskirts of Antananarivo, Madagascar. Cockfighting is held during the week end and is a tradition with asian roots still practiced in Madagascar. (Photo by Gianluigi Guercia/AFP Photo)

(L-R) Natalie Burns and Taunia Arave battle as referee Nick Stevens (R) looks on during the US National Sumo Championships at the Riviera Hotel & Casino June 24, 2011 in Las Vegas, Nevada. (Photo by Ethan Miller/Getty Images)

Going toe-to-toe, these fighting primates could give Floyd Mayweather a run for his money. The amazing images – captured by Australian tourist Julie Rathbone on the banks of the Zambezi river in Africa – show the pair engaging in a few fisticuffs. The Chacma baboons appeared to settle a disagreement by fighting – before a senior baboon plays referee and steps in to break it up. Nurse unit manager Julie Rathbone, 59, from New South Wales, was on a cruise down the river when she spotted the fracas unfolding. (Photo by Julie Rathbone/Caters News)

A female referee counts as member of Uganda's Soft Ground Wrestling is pinned to the ground during a training session at their camp in Mukono on February 28, 202. Uganda's Soft Ground Wrestling is getting attention worldwide and becoming an Internet sensation. Members showcase their wrestling skills on their YouTube channel, performing inside makeshift bamboo ring posts with string ropes and soil. Currently, Soft Ground Wrestling has 200 members, most of them from unprivileged backgrounds, and include both men and women training vigorously as they dream of becoming professional wrestlers. (Photo by Badru Katumba/AFP Photo)

A young YPJ recruit (in pink) arrives to the training base for her first day in training near Derek City, Syria. The YPJ schedule is demanding and requires discipline – new soldiers in training get about 6 hours of sleep a night and wake up at 4 AM to begin exercising; afterwards, their day consists of a full schedule of drills and classroom lessons. Before joining the YPJ many of the girls had never participated in physical activity or sports before. (Photo by Erin Trieb/NBC News)

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)

1: Dubai's Burj Khalifa is the tallest building in the world, but perhaps not for long. Saudi Arabia has announced plans to build a 1 kilometer (3,280 foot) tower into the sky, to be named the Jeddah Tower, scheduled for completion in 2020. The Burj Khallifa currently stands at 2,716 ft. (Photo by Matthias Seifert/Reuters)

An Orthodox priest conducts a blessing in front of the Soyuz TMA-20M for the next International Space Station (ISS) crew, comprised of Jeff Williams of the U.S. and Oleg Skriprochka and Alexey Ovchinin of Russia, at the launchpad at the Baikonur cosmodrome, Kazakhstan, March 17, 2016, ahead of its launch scheduled on March 19. (Photo by Shamil Zhumatov/Reuters)