Roger Federer maintains Group B bid with straight sets victory over Stan Wawrinka . Defeat for the Scot would have spelled early elimination . Nishikori , who lacked the poise he showed when beating Murray on Sunday , showered praise on the evergreen Federer afterwards . Andy Murray rolls back Thursday with vintage display against Kei Nishikori . All four players in Group B can still qualify for semifinals .
Roger Federer maintains Group B bid with straight sets victory over Stan Wawrinka . Defeat for the Scot would have spelled early elimination . Andy Murray rolls back Thursday with vintage display against Kei Nishikori . All four players in Group B can still qualify for semifinals .