2017 Nitto ATP FINALS Jack Sock (USA) defeated Marin Cilic (CRO) 57 62 76(4) Photo © Ray Giubilo This image may not be reproduced or sold to third parties.

2017 Nitto ATP FINALS Jack Sock (USA) defeated Marin Cilic (CRO) 57 62 76(4) Photo © Ray Giubilo This image may not be reproduced or sold to third parties.

2017 Nitto ATP FINALS Roger Federer (SUI) vs Alexander Zverev (GER) Photo © Ray Giubilo This image may not be reproduced or sold to third parties.

2017 Nitto ATP FINALS Grigor Dimitrov (BUL) defeated David Goffin (BEL) 60 62 Photo © Ray Giubilo This image may not be reproduced or sold to third parties.

Katerina Siniakova (CZE) Tennis - AUSTRALIAN OPEN 2016 - Grand Slam ATP / WTA - Melbourne Park - Melbourne - Victoria - Australia - 19 January 2016.