Stefanos Tsitsipas won his opening match of the ATP Next Gen Finals with a comfortable victory over Jaume Munar in Milan.
The world No. 15 defeated Spaniard Munar 4-3 (5), 4-3 (3), 3-4(4), 4-2 in the Group A match.
Second seed Alex de Minaur cruised to a straight-sets win in his Group B opener, defeating Liam Caruana 4-1, 4-1, 4-2.
No. 3 seed Frances Tiafoe also secured a victory in his Group A opener in a hard-fought encounter against Hubert Hurkacz. The American won the match 4-1, 4-2, 2-4, 4-3(10) in one hour and 22 minutes of play.
There was a five-set thriller in Group B as Russian Andrey Rublev defeated American Taylor Fritz 4-2, 1-4, 3-4(4), 4-3(2), 4-2.