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AUCKLAND, NEW ZEALAND - JANUARY 11: Matthew Barton of Australia returns a shot to Steve Johnson of USA during day one of the men's 2016 ASB Classic at the ASB Tennis Centre on January 11, 2016 in Auckland, New Zealand. (Photo by Fiona Goodall/Getty Images)

AUCKLAND, NEW ZEALAND - JANUARY 11:  Matthew Barton of Australia returns a shot to Steve Johnson of USA during day one of the men's 2016 ASB Classic at the ASB Tennis Centre on January 11, 2016 in Auckland, New Zealand.  (Photo by Fiona Goodall/Getty Images)