Results from the first day of the ATP Finals at London's O2 Arena on Sunday (x denotes seeding): Singles Group London 2020 Dominic Thiem (AUT x3) bt Stefanos Tsitsipas (GRE x6) 7-6 (7/5), 4-6, 6-3 Rafael Nadal (ESP x2) bt Andrey Rublev (RUS x7) 6-3, 6-4 Doubles Group Mike Bryan Wesley Koolhof/Nikola Mektic (NED/CRO x5) bt Kevin Krawietz/Andreas Mies (GER/GER x3) 6-7 (3/7), 7-6 (7/4), 10-7 Rajeev Ram/Joe Salisbury (USA/GBR x2) bt Lukasz Kubot/Marcelo Melo (POL/BRA x8) 7-5, 3-6, 10-5 afp