Roger Federer faces an uphill task to qualify for the last four of the ATP Finals after defeat by Dominic Thiem on Sunday following a masterclass by Novak Djokovic.
Six-time champion Federer was beaten 7-5, 7-5 in the evening match on the opening day after Djokovic had swatted aside debutant Matteo Berrettini in the earlier Group Bjorn Borg contest in London. Federer and Djokovic will meet later in the week in a repeat of this year's epic Wimbledon final, with two players advancing from the four-man group.
