Wawrinka leads Nishikori 4 - 3 in their FedEx ATP Head2Head series .
Nishikori beat Wawrinka 6 - 2 .
Wawrinka leads Nishikori 4 - 3 in their FedEx ATP Head2Head series , although Nishikori beat Wawrinka 6 - 2 .