Briton Andy Murray has made a disappointing start to the ATP World Tour Finals in London. He lost his opening group match against Kei Nishikori of Japan in straight sets, 4-6, 4-6. In the other Group-B match, world number two Roger Federer defeated Canada's Milos Raonic, 6-1, 7-6.In their Group-A openers today, world number one Novak Djokovic will meet Marin Cilic, while Stanislas Wawrinka will take on Tomas Berdych.