Nishikori shocks off-form Federer, Anderson upsets Thiem at ATP finals

Roger Federer of Switzerland reacts during the men's single match between Roger Federer of Switzerland and Kei Nishikori of Japan on Day One of the ATP World Tour Finals at the O2 Arena in London, Britain on Nov. 11, 2018. Federer lost 0-2. (Xinhua/Han Yan)