Tennis - French Open - Roland Garros, Paris, France - 31/5/17 Bulgaria's Grigor Dimitrov celebrates after winning his second round match against Spain's Tommy Robredo Reuters / Christian Hartmann 

Tennis - French Open - Roland Garros, Paris, France - 31/5/17 Bulgaria's Grigor Dimitrov celebrates after winning his second round match against Spain's Tommy Robredo Reuters / Christian Hartmann 

Tennis - French Open - Roland Garros, Paris, France - 31/5/17 Bulgaria's Grigor Dimitrov shakes the hand of Spain's Tommy Robredo after winning their second round match Reuters / Christian Hartmann 

Tennis - French Open - Roland Garros, Paris, France - 31/5/17 Bulgaria's Grigor Dimitrov in action during his second round match against Spain's Tommy Robredo Reuters / Christian Hartmann 

Tennis - French Open - Roland Garros, Paris, France - 31/5/17 Spain's Tommy Robredo in action during his second round match against Bulgaria's Grigor Dimitrov Reuters / Christian Hartmann 

Tennis - French Open - Roland Garros, Paris, France - 31/5/17 Spain's Tommy Robredo in action during his second round match against Bulgaria's Grigor Dimitrov Reuters / Christian Hartmann 

Tennis - French Open - Roland Garros, Paris, France - 31/5/17 Spain's Tommy Robredo in action during his second round match against Bulgaria's Grigor Dimitrov Reuters / Christian Hartmann 

Tennis - French Open - Roland Garros, Paris, France - 31/5/17 Bulgaria's Grigor Dimitrov in action during his second round match against Spain's Tommy Robredo Reuters / Christian Hartmann 

Tennis - French Open - Roland Garros, Paris, France - 31/5/17 Bulgaria's Grigor Dimitrov in action during his second round match against Spain's Tommy Robredo Reuters / Christian Hartmann 

Tennis - French Open - Roland Garros, Paris, France - 31/5/17 Bulgaria's Grigor Dimitrov in action during his second round match against Spain's Tommy Robredo Reuters / Christian Hartmann 

Tennis - French Open - Roland Garros, Paris, France - 31/5/17 Bulgaria's Grigor Dimitrov in action during his second round match against Spain's Tommy Robredo Reuters / Christian Hartmann 

Tennis - French Open - Roland Garros, Paris, France - 31/5/17 Spain's Tommy Robredo in action during his second round match against Bulgaria's Grigor Dimitrov Reuters / Christian Hartmann 

Tennis - French Open - Roland Garros, Paris, France - 31/5/17 Spain's Tommy Robredo in action during his second round match against Bulgaria's Grigor Dimitrov Reuters / Christian Hartmann 

Tennis - French Open - Roland Garros, Paris, France - 31/5/17 Spain's Tommy Robredo in action during his second round match against Bulgaria's Grigor Dimitrov Reuters / Christian Hartmann 

Tennis - French Open - Roland Garros, Paris, France - 31/5/17 Bulgaria's Grigor Dimitrov in action during his second round match against Spain's Tommy Robredo Reuters / Christian Hartmann 

Tennis - French Open - Roland Garros, Paris, France - 31/5/17 Bulgaria's Grigor Dimitrov in action during his second round match against Spain's Tommy Robredo Reuters / Christian Hartmann 

Tennis - French Open - Roland Garros, Paris, France - 31/5/17 Bulgaria's Grigor Dimitrov in action during his second round match against Spain's Tommy Robredo Reuters / Christian Hartmann 

Novak Djokovic of Serbia returns the ball to Tommy Robredo of Spain during their ATP tennis match on the first round of the Dubai Duty Free Tennis Championships February 22, 2016. REUTERS/Ahmed Jadallah

Novak Djokovic of Serbia returns the ball to Tommy Robredo of Spain during their ATP tennis match on the first round of the Dubai Duty Free Tennis Championships February 22, 2016. REUTERS/Ahmed Jadallah

Novak Djokovic of Serbia returns the ball to Tommy Robredo of Spain during their ATP tennis match on the first round of the Dubai Duty Free Tennis Championships February 22, 2016. REUTERS/Ahmed Jadallah

Novak Djokovic of Serbia returns the ball to Tommy Robredo of Spain during their ATP tennis match on the first round of the Dubai Duty Free Tennis Championships February 22, 2016. REUTERS/Ahmed Jadallah

Novak Djokovic of Serbia returns the ball to Tommy Robredo of Spain during their ATP tennis match on the first round of the Dubai Duty Free Tennis Championships February 22, 2016. REUTERS/Ahmed Jadallah

Novak Djokovic of Serbia returns the ball to Tommy Robredo of Spain during their ATP tennis match on the first round of the Dubai Duty Free Tennis Championships February 22, 2016. REUTERS/Ahmed Jadallah

Novak Djokovic of Serbia returns the ball to Tommy Robredo of Spain during their ATP tennis match on the first round of the Dubai Duty Free Tennis Championships February 22, 2016. REUTERS/Ahmed Jadallah

Novak Djokovic of Serbia returns the ball to Tommy Robredo of Spain during their ATP tennis match on the first round of the Dubai Duty Free Tennis Championships February 22, 2016. REUTERS/Ahmed Jadallah

Novak Djokovic of Serbia returns the ball to Tommy Robredo of Spain during their ATP tennis match on the first round of the Dubai Duty Free Tennis Championships February 22, 2016. REUTERS/Ahmed Jadallah

Tommy Robredo of Spain returns the ball to Novak Djokovic of Serbia during their ATP tennis match on the first round of the Dubai Duty Free Tennis Championships February 22, 2016. REUTERS/Ahmed Jadallah

Novak Djokovic of Serbia serves to Tommy Robredo of Spain during their ATP tennis match on the first round of the Dubai Duty Free Tennis Championships February 22, 2016. REUTERS/Ahmed Jadallah

Tommy Robredo of Spain returns the ball to Novak Djokovic of Serbia during their ATP tennis match on the first round of the Dubai Duty Free Tennis Championships February 22, 2016. REUTERS/Ahmed Jadallah

Novak Djokovic of Serbia returns the ball to Tommy Robredo of Spain during their ATP tennis match on the first round of the Dubai Duty Free Tennis Championships February 22, 2016. REUTERS/Ahmed Jadallah

Tommy Robredo of Spain returns the ball to Novak Djokovic of Serbia during their ATP tennis match on the first round of the Dubai Duty Free Tennis Championships February 22, 2016. REUTERS/Ahmed Jadallah

Novak Djokovic of Serbia returns the ball to Tommy Robredo of Spain during their ATP tennis match on the first round of the Dubai Duty Free Tennis Championships February 22, 2016. REUTERS/Ahmed Jadallah

Novak Djokovic of Serbia returns the ball to Tommy Robredo of Spain during their ATP tennis match on the first round of the Dubai Duty Free Tennis Championships February 22, 2016. REUTERS/Ahmed Jadallah

Novak Djokovic of Serbia returns the ball to Tommy Robredo of Spain during their ATP tennis match on the first round of the Dubai Duty Free Tennis Championships February 22, 2016. REUTERS/Ahmed Jadallah

Novak Djokovic of Serbia returns the ball to Tommy Robredo of Spain during their ATP tennis match on the first round of the Dubai Duty Free Tennis Championships February 22, 2016. REUTERS/Ahmed Jadallah

Novak Djokovic of Serbia returns the ball to Tommy Robredo of Spain during their ATP tennis match on the first round of the Dubai Duty Free Tennis Championships February 22, 2016. REUTERS/Ahmed Jadallah

Novak Djokovic of Serbia returns the ball to Tommy Robredo of Spain during their ATP tennis match on the first round of the Dubai Duty Free Tennis Championships February 22, 2016. REUTERS/Ahmed Jadallah

Novak Djokovic of Serbia returns the ball to Tommy Robredo of Spain during their ATP tennis match on the first round of the Dubai Duty Free Tennis Championships February 22, 2016. REUTERS/Ahmed Jadallah

Novak Djokovic of Serbia returns the ball to Tommy Robredo of Spain during their ATP tennis match on the first round of the Dubai Duty Free Tennis Championships February 22, 2016. REUTERS/Ahmed Jadallah

Tommy Robredo of Spain returns the ball to Novak Djokovic of Serbia during their ATP tennis match on the first round of the Dubai Duty Free Tennis Championships February 22, 2016. REUTERS/Ahmed Jadallah

Novak Djokovic of Serbia returns the ball to Tommy Robredo of Spain during their ATP tennis match on the first round of the Dubai Duty Free Tennis Championships February 22, 2016. REUTERS/Ahmed Jadallah

Tommy Robredo of Spain returns the ball to Novak Djokovic of Serbia during their ATP tennis match on the first round of the Dubai Duty Free Tennis Championships February 22, 2016. REUTERS/Ahmed Jadallah

Tommy Robredo of Spain returns the ball to Novak Djokovic of Serbia during their ATP tennis match on the first round of the Dubai Duty Free Tennis Championships February 22, 2016. REUTERS/Ahmed Jadallah

Novak Djokovic of Serbia returns the ball to Tommy Robredo of Spain during their ATP tennis match on the first round of the Dubai Duty Free Tennis Championships February 22, 2016. REUTERS/Ahmed Jadallah

Canada's Milos Raonic signs autographs after winning his second round match against Spain's Tommy Robredo at the Australian Open tennis tournament at Melbourne Park, Australia, January 21, 2016. REUTERS/Issei Kato 

Canada's Milos Raonic signs autographs after winning his second round match against Spain's Tommy Robredo at the Australian Open tennis tournament at Melbourne Park, Australia, January 21, 2016. REUTERS/Issei Kato TPX IMAGES OF THE DAY 

Spain's Tommy Robredo waves as he leaves after losing his second round match against Canada's Milos Raonic at the Australian Open tennis tournament at Melbourne Park, Australia, January 21, 2016. REUTERS/Issei Kato 

Canada's Milos Raonic celebrates after winning his second round match against Spain's Tommy Robredo at the Australian Open tennis tournament at Melbourne Park, Australia, January 21, 2016. REUTERS/Issei Kato TPX IMAGES OF THE DAY 

Canada's Milos Raonic celebrates after winning his second round match against Spain's Tommy Robredo at the Australian Open tennis tournament at Melbourne Park, Australia, January 21, 2016. REUTERS/Issei Kato 

Canada's Milos Raonic celebrates after winning his second round match against Spain's Tommy Robredo at the Australian Open tennis tournament at Melbourne Park, Australia, January 21, 2016. REUTERS/Issei Kato 

Canada's Milos Raonic celebrates after winning his second round match against Spain's Tommy Robredo at the Australian Open tennis tournament at Melbourne Park, Australia, January 21, 2016. REUTERS/Issei Kato 

Canada's Milos Raonic celebrates after winning his second round match against Spain's Tommy Robredo at the Australian Open tennis tournament at Melbourne Park, Australia, January 21, 2016. REUTERS/Issei Kato 

Canada's Milos Raonic reacts after winning his second round match against Spain's Tommy Robredo at the Australian Open tennis tournament at Melbourne Park, Australia, January 21, 2016. REUTERS/Issei Kato 

Canada's Milos Raonic hits a shot during his second round match against Spain's Tommy Robredo at the Australian Open tennis tournament at Melbourne Park, Australia, January 21, 2016. REUTERS/Issei Kato 

Canada's Milos Raonic hits a shot during his second round match against Spain's Tommy Robredo at the Australian Open tennis tournament at Melbourne Park, Australia, January 21, 2016. REUTERS/Issei Kato 

Spain's Tommy Robredo stretches to hit a shot during his second round match against Canada's Milos Raonic at the Australian Open tennis tournament at Melbourne Park, Australia, January 21, 2016. REUTERS/Issei Kato 

Spain's Tommy Robredo serves during his second round match against Canada's Milos Raonic at the Australian Open tennis tournament at Melbourne Park, Australia, January 21, 2016. REUTERS/Issei Kato 

Spain's Tommy Robredo runs to hit a shot during his first round match against Tunisia's Malek Jaziri at the Australian Open tennis tournament at Melbourne Park, Australia, January 19, 2016. REUTERS/John French 

Tunisia's Malek Jaziri reacts after missing a shot during his first round match against Spain's Tommy Robredo at the Australian Open tennis tournament at Melbourne Park, Australia, January 19, 2016. REUTERS/John French 

Spain's Tommy Robredo (L) shakes hands with Tunisia's Malek Jaziri after Robredo won their first round match at the Australian Open tennis tournament at Melbourne Park, Australia, January 19, 2016. REUTERS/John French