Serbian tennis player Novak Djokovic (C), accompanied by his father Srdjan Djokovic (L) and his mother Dijana Djokovic, celebrates 311 weeks as world number one with his family and supporters in front of family restaurant "Novak" in Belgrade, on March 8, 2021. Novak Djokovic set a new landmark of 311 weeks as world number one on March 8, 2021, one week longer than Roger Federer whose tally of a record 20 Grand Slam titles is now firmly in the Serb's sights. "Big day today," the tennis superstar wrote on Twitter. Djokovic, 33, won his 18th major at the Australian Open in February.,Image: 596070758, License: Rights-managed, Restrictions: , Model Release: no, Credit line: Profimedia

PARIS, FRANCE - JUNE 05: Novak Djokovic of Serbia celebrates victory with his parents, Dijana and Srdan Djokovic during the Men's Singles final match against Andy Murray of Great Britain on day fifteen of the 2016 French Open at Roland Garros on June 5, 2016 in Paris, France. (Photo by Julian Finney/Getty Images)

Serbia's Novak Djokovic's father Srdjan gestures during a press conference in Belgrade, Serbia, Monday, Jan. 10, 2022. Tennis star Novak Djokovic on Monday won a court battle to stay in Australia to contest the Australian Open despite being unvaccinated against COVID-19, but the government threatened to cancel his visa a second time. Federal Circuit Court Judge Anthony Kelly reinstated Djokovic's visa, which was canceled after his arrival last week because officials decided he didn't meet the criteria for an exemption to an entry requirement that all non-citizens be fully vaccinated. (AP Photo/Darko Vojinovic)

Serbia's Novak Djokovic's father Srdjan gestures during a press conference in Belgrade, Serbia, Monday, Jan. 10, 2022. Tennis star Novak Djokovic on Monday won a court battle to stay in Australia to contest the Australian Open despite being unvaccinated against COVID-19, but the government threatened to cancel his visa a second time. Federal Circuit Court Judge Anthony Kelly reinstated Djokovic's visa, which was canceled after his arrival last week because officials decided he didn't meet the criteria for an exemption to an entry requirement that all non-citizens be fully vaccinated. (AP Photo/Darko Vojinovic)