Japan's Kei Nishikori sitting out Davis Cup quarterfinal with injury Kei Nishikori isn't sure how long he'll be out with a groin injury, which also kept him out of last week's match against Novak Djokovic. Geoff Burke / USA TODAY Sports AP Apr 2, 2014 at 12:31p ET TOKYO -- Kei Nishikori says he will sit out Japan's Davis Cup quarterfinal against the Czech Republic this weekend because of a groin injury. Nishikori beat Roger Federer in the Sony Open quarterfinals last week, but he had to withdraw from the semifinal against Novak Djokovic because of pain in his left groin. Nishikori has retired or withdrawn 14 times in his career, including three times in Grand Slam events. He said he won't need surgery, but he's unsure how long he'll be sidelined. Nishikori's absence hurts Japan's chances of beating the two-time defending champion Czechs in their first tie since 1935.