Gold medalist Andy Murray poses during the podium ceremony of the men's singles gold medal tennis event at the Olympic Tennis Center in Rio on Sunday. Luis Acosta/AFP/Getty Images hide caption

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Serbia's Novak Djokovic kisses the trophy after winning the final of the French Open tennis tournament against Britain's Andy Murray in four sets 3-6, 6-1, 6-2, 6-4, at the Roland Garros stadium in Paris, Sunday. Michel Euler/AP hide caption

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Serbia's Novak Djokovic has won the Australian Open six times — in 2008, 2011, 2012, 2013 and 2015, and then on Sunday. William West/AFP/Getty Images hide caption

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Roger Federer of Switzerland (left) and Andy Murray of Great Britain hold up their trophies after the men's singles final match at Wimbledon Sunday. Clive Brunskill/Getty Images hide caption

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