The combo photo shows: (Top, L) Rafael Nadal of Spain holds the champion trophy after winning the men's singles final match against Daniil Medvedev of Russia at the 2019 US Open in New York, the United States, Sept. 8, 2019; (Top, R) Novak Djokovic of Serbia kisses the champion trophy after winning the men's singles final against Roger Federer of Switzerland at the 2019 Wimbledon Tennis Championships in London, Britain, July 14, 2019; (Bottom, L) Novak Djokovic of Serbia kisses the champion trophy after winning the men's singles final match against Rafael Nadal of Spain at 2019 Australian Open in Melbourne, Australia, Jan. 27, 2019; (Bottom, R) Rafael Nadal of Spain holds the champion trophy after winning the men's singles final match against Dominic Thiem of Austria at French Open tennis tournament 2019 at Roland Garros in Paris, France, June 9, 2019. Spanish tennis legend Rafael Nadal and Serbian superstar Novak Djokovic shared the four Grand Slams in 2019, as Nadal won a record-extending 12th French Open title in addition to the U.S. Open, while Djokovic claimed the Australian Open and Wimbledon titles. (Xinhua)