![ROTTERDAM, THE NETHERLANDS - MARCH 2: Karen Khachanov of Russia during his match against Stan Wawrinka of Switzerland during the 48e ABN AMRO World Te Stock Photo - Alamy ROTTERDAM, THE NETHERLANDS - MARCH 2: Karen Khachanov of Russia during his match against Stan Wawrinka of Switzerland during the 48e ABN AMRO World Te Stock Photo - Alamy](https://c8.alamy.com/comp/2EW808D/rotterdam-the-netherlands-march-2-karen-khachanov-of-russia-during-his-match-against-stan-wawrinka-of-switzerland-during-the-48e-abn-amro-world-te-2EW808D.jpg)
ROTTERDAM, THE NETHERLANDS - MARCH 2: Karen Khachanov of Russia during his match against Stan Wawrinka of Switzerland during the 48e ABN AMRO World Te Stock Photo - Alamy
![26th October 2017, St Jakobshalle, Basel, Switzerland ATP Tennis Herren World Tour 500, Swiss Indoors Te 26th October 2017, St Jakobshalle, Basel, Switzerland ATP Tennis Herren World Tour 500, Swiss Indoors Te](https://www.imago-images.com/bild/sp/0030731320/w.jpg)
26th October 2017, St Jakobshalle, Basel, Switzerland ATP Tennis Herren World Tour 500, Swiss Indoors Te
![ROTTERDAM, THE NETHERLANDS - MARCH 2: Karen Khachanov of Russia during his match against Stan Wawrinka of Switzerland during the 48e ABN AMRO World Te Stock Photo - Alamy ROTTERDAM, THE NETHERLANDS - MARCH 2: Karen Khachanov of Russia during his match against Stan Wawrinka of Switzerland during the 48e ABN AMRO World Te Stock Photo - Alamy](https://c8.alamy.com/comp/2EW7WG3/rotterdam-the-netherlands-march-2-karen-khachanov-of-russia-during-his-match-against-stan-wawrinka-of-switzerland-during-the-48e-abn-amro-world-te-2EW7WG3.jpg)
ROTTERDAM, THE NETHERLANDS - MARCH 2: Karen Khachanov of Russia during his match against Stan Wawrinka of Switzerland during the 48e ABN AMRO World Te Stock Photo - Alamy
![Belinda Bencic of Switzerland plays a backhand against Beatriz Haddad Maia of Brazil during the Sydney Te Belinda Bencic of Switzerland plays a backhand against Beatriz Haddad Maia of Brazil during the Sydney Te](https://www.imago-images.com/bild/sp/1009069021/w.jpg)
Belinda Bencic of Switzerland plays a backhand against Beatriz Haddad Maia of Brazil during the Sydney Te
![Roger Federer of Switzerland returns the ball during the men s semifinal match on the BNP Paribas Open te Roger Federer of Switzerland returns the ball during the men s semifinal match on the BNP Paribas Open te](https://www.imago-images.com/bild/sp/0019334327/w.jpg)
Roger Federer of Switzerland returns the ball during the men s semifinal match on the BNP Paribas Open te
![Mandatory Credit Photo by Shutterstock (12194410bh) Roger Federer of Switzerland in action Wimbledon Te Mandatory Credit Photo by Shutterstock (12194410bh) Roger Federer of Switzerland in action Wimbledon Te](https://www.imago-images.com/bild/sp/1003492287/w.jpg)
Mandatory Credit Photo by Shutterstock (12194410bh) Roger Federer of Switzerland in action Wimbledon Te
![Roger Federer of Switzerland stands with Qatari Tennis team children during the opening of the Qatar Open tennis tournament in Doha January 3, 2011. REUTERS/Jamal Saidi (QATAR - Tags: SPORT TENNIS Stock Roger Federer of Switzerland stands with Qatari Tennis team children during the opening of the Qatar Open tennis tournament in Doha January 3, 2011. REUTERS/Jamal Saidi (QATAR - Tags: SPORT TENNIS Stock](https://c8.alamy.com/comp/2D0DKYM/roger-federer-of-switzerland-stands-with-qatari-tennis-team-children-during-the-opening-of-the-qatar-open-tennis-tournament-in-doha-january-3-2011-reutersjamal-saidi-qatar-tags-sport-tennis-2D0DKYM.jpg)
Roger Federer of Switzerland stands with Qatari Tennis team children during the opening of the Qatar Open tennis tournament in Doha January 3, 2011. REUTERS/Jamal Saidi (QATAR - Tags: SPORT TENNIS Stock
![26th October 2017, St Jakobshalle, Basel, Switzerland ATP Tennis Herren World Tour 500, Swiss Indoors Te 26th October 2017, St Jakobshalle, Basel, Switzerland ATP Tennis Herren World Tour 500, Swiss Indoors Te](https://www.imago-images.com/bild/sp/0030731309/w.jpg)