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BASEL, SWITZERLAND - OCTOBER 29: Kei Nishikori of Japan shakes hands with Gilles Muller of Luxembourg following the Swiss Indoors ATP 500 tennis tournament semi-final match at St Jakobshalle on October 29, 2016 in Basel, Switzerland. (Photo by Harold Cunningham/Getty Images)

BASEL, SWITZERLAND - OCTOBER 29:  Kei Nishikori of Japan shakes hands with Gilles Muller of Luxembourg following the Swiss Indoors ATP 500 tennis tournament semi-final match at St Jakobshalle on October 29, 2016 in Basel, Switzerland.  (Photo by Harold Cunningham/Getty Images)