Sydney: Alexander Zverev and Stefanos Tsitsipas both crashed to defeat in their first matches of the year Friday as day one of the inaugural ATP Cup sprung some big upsets. The German World No. 7 was stunned by Australia's fast-improving Alex de Minaur, who rallied from a set and 4-2 down to win 4-6, 7-6 (7/3), 6-2. Greek star Tsitsipas, who won the 2019 season-ending ATP Finals in London and is now ranked six, slumped to a 7-6 (8-6), 7-6 (7/4) loss to young Canadian Denis Shapovalov. It led to both Germany and Greece being defeated in their opening ties at the 24-nation event, where the countries are split into six groups across Sydney, Brisbane and Perth.

The top eight from the round robin go onto the knockout phase in Sydney before one is eventually crowned the winner.