20 of the world's top male tennis players came together for a tournament. They were sorted into four round-robin groups of five (shown in COLUMNS) and played one best of three set match against each player in their group. The top two in each qualified to the knockout stages. Numbers in brackets denotes tournament seeds. Three letters in brackets denotes country. This quiz has to be a minefield to work - be careful! Very little knowledge of tennis and geography is required. See comments for country abbreviations. Below: Tournament Tree (also in comments) Sets difference=sets won - sets lost.