The first round of the Australian Open continues on Monday at Melbourne Park where top seed and defending champion Jannik Sinner seeks a third Grand Slam title while Novak Djokovic begins his quest for a record-extending 25th major.

A Grand Slam or Major tournament is the highest-tier event in tennis. It starts with the Australian Open in January, then the French Open in June, Wimbledon in July, and finally the US Open in September.

Grand Slam winners' checks are some of the richest in the sport, but proportionally the players get a rawer deal than their counterparts.