Results on the seventh day of the ATP Finals at London's O2 Arena on Saturday (x denotes seeding): Singles Semi-finals Dominic Thiem (AUT x3) bt Novak Djokovic (SRB x1) 7-5, 6-7 (10/12), 7-6 (7/5) Playing later Rafael Nadal (ESP x2) v Daniil Medvedev (RUS x4) Doubles Semi-finals Wesley Koolhof/Nikola Mektic (NED/CRO x5) bt Marcel Granollers/Horacio Zeballos (ESP/ARG x4) 6-3, 6-4 Playing later Rajeev Ram/Joe Salisbury (USA/GBR x2) v Jurgen Melzer/Edouard Roger-Vasselin (AUT/FRA x7) afp