Tennis - Australian Open - Fourth Round - Melbourne Park, Melbourne, Australia, January 20, 2019. Andre Agassi, coach of Bulgaria's Grigor Dimitrov, watches Dimitrov's match against Frances Tiafoe of the U.S. REUTERS/Edgar Su 

Tennis - Australian Open - Fourth Round - Melbourne Park, Melbourne, Australia, January 20, 2019. Andre Agassi (2nd R), coach of Bulgaria's Grigor Dimitrov, cheers Dimitrov on during the match against Frances Tiafoe of the U.S. REUTERS/Edgar Su 

Tennis - Australian Open - Melbourne Park, Melbourne, Australia - January 13, 2019 - Bulgaria's Grigor Dimitrov practices as his coach Andre Agassi looks on. REUTERS/Adnan Abidi 

Tennis - Australian Open - Rod Laver Arena, Melbourne, Australia, January 22, 2018. Serbia's Novak Djokovic and his coaches Andre Agassi and Radek Stepanek react during his match against South Korea's Chung Hyeon. REUTERS/Edgar Su 

Tennis - Australian Open - Rod Laver Arena, Melbourne, Australia, January 22, 2018. Andre Agassi and Radek Stepanek, coaches of Novak Djokovic of Serbia, watch Djokovic's match against Chung Hyeon of South Korea. REUTERS/Issei Kato 

Tennis - Australian Open - Rod Laver Arena, Melbourne, Australia, January 22, 2018. Andre Agassi, coach of Novak Djokovic of Serbia, watches Djokovic's match against Chung Hyeon of South Korea. REUTERS/Issei Kato 

Tennis - Australian Open - Margaret Court Arena, Melbourne, Australia, January 20, 2018. Andre Agassi coach of Serbia's Novak Djokovic in the stands during his match against Spain's Albert Ramos-Vinolas. REUTERS/Issei Kato 

Tennis - Australian Open - Margaret Court Arena, Melbourne, Australia, January 20, 2018. Andre Agassi coach of Serbia's Novak Djokovic in the stands before his match against Spain's Albert Ramos-Vinolas. REUTERS/Issei Kato 

Tennis - Australian Open - Rod Laver Arena, Melbourne, Australia, January 18, 2018. Andre Agassi and Radek Stepanek, coaches of Novak Djokovic of Serbia, celebrate after Djokovic won his match against Gael Monfils of France. REUTERS/David Gray 

Tennis - Australian Open - Rod Laver Arena, Melbourne, Australia, January 18, 2018. Andre Agassi and Radek Stepanek, coaches of Novak Djokovic of Serbia, watch his match against Gael Monfils of France. REUTERS/Thomas Peter 

Tennis - Australian Open - Margaret Court Arena, Melbourne, Australia, January 16, 2018. Andre Agassi, coach of Novak Djokovic of Serbia, is pictured before Djokovic's match against Donald Young of the U.S. REUTERS/Issei Kato 

Tennis - Australian Open - Melbourne, Australia, January 14, 2018. Novak Djokovic of Serbia speaks with his coach Andre Agassi during a practice session before the Australian Open tennis tournament. REUTERS/Issei Kato 

Tennis - Australian Open - Melbourne, Australia, January 14, 2018. Andre Agassi, coach of Novak Djokovic of Serbia, is silhouetted as he watches Djokovic during a practice session before the Australian Open tennis tournament. REUTERS/Issei Kato TPX IMAGES OF THE DAY 

Tennis - Australian Open - Melbourne, Australia, January 14, 2018. Novak Djokovic of Serbia speaks with his coach Andre Agassi during a break in a practice session before the Australian Open tennis tournament. REUTERS/Issei Kato 

Tennis - Australian Open - Melbourne, Australia, January 14, 2018. Novak Djokovic of Serbia speaks with his coach Andre Agassi during a practice session before the Australian Open tennis tournament. REUTERS/Issei Kato 

Tennis - Australian Open - Melbourne, Australia, January 14, 2018. Novak Djokovic of Serbia walks past his coach Andre Agassi during a practice session before the Australian Open tennis tournament. REUTERS/Issei Kato 

Tennis - Australian Open - Melbourne, Australia, January 14, 2018. Novak Djokovic of Serbia walks past his coach Andre Agassi during a practice session before the Australian Open tennis tournament. REUTERS/Issei Kato 

Tennis - Australian Open - Melbourne, Australia, January 14, 2018. Novak Djokovic of Serbia speaks with his coach Andre Agassi during a practice session before the Australian Open tennis tournament. REUTERS/Toru Hanai 

Tennis - Australian Open - Melbourne, Australia, January 14, 2018. Novak Djokovic of Serbia speaks with his coach Andre Agassi during a practice session before the Australian Open tennis tournament. REUTERS/Toru Hanai 

Tennis - Wimbledon - London, Britain - July 11, 2017 Serbia’s Novak Djokovic's coach Andre Agassi before the fourth round match against France’s Adrian Mannarino REUTERS/Matthew Childs 

Tennis - Wimbledon - London, Britain - July 8, 2017 Andre Agassi, coach of Serbia's Novak Djokovic in the stands on centre court during his third round match against Latvia’s Ernests Gulbis REUTERS/Andrew Couldridge 

Tennis - Wimbledon - London, Britain - July 8, 2017 Andre Agassi, coach of Serbia's Novak Djokovic in the stands on centre court before his third round match against Latvia’s Ernests Gulbis REUTERS/Andrew Couldridge 

Tennis - Wimbledon - London, Britain - July 8, 2017 Andre Agassi, coach of Serbia's Novak Djokovic in the stands on centre court before his third round match against Latvia’s Ernests Gulbis REUTERS/Andrew Couldridge 

Tennis - Wimbledon - London, Britain - July 4, 2017 Andre Agassi, coach of Serbia's Novak Djokovic on centre court REUTERS/Matthew Childs 

Tennis - French Open - Roland Garros, Paris, France - June 2, 2017 Andre Agassi coach of Serbia's Novak Djokovic looks on Reuters / Gonzalo Fuentes 

Tennis - French Open - Roland Garros, Paris, France - June 2, 2017 Andre Agassi coach of Serbia's Novak Djokovic looks on Reuters / Gonzalo Fuentes 

Tennis - French Open - Roland Garros, Paris, France - 31/5/17 Coach of Serbia's Novak Djokovic, Andre Agassi watches during his second round match against Portugal's Joao Sousa Reuters / Gonzalo Fuentes 

Tennis - French Open - Roland Garros, Paris, France - 31/5/17 Coach of Serbia's Novak Djokovic, Andre Agassi watches during his second round match against Portugal's Joao Sousa Reuters / Gonzalo Fuentes 

Tennis - French Open - Roland Garros, Paris, France - 29/5/17 Andre Agassi coach of Serbia's Novak Djokovic Reuters / Gonzalo Fuentes 

Tennis - French Open - Roland Garros, Paris, France - 29/5/17 Andre Agassi coach of Serbia's Novak Djokovic Reuters / Gonzalo Fuentes 

Tennis - French Open - Roland Garros - Paris - 26/05/2017 - Novak Djokovic of Serbia and his coach Andre Agassi attend a training session. REUTERS/Benoit Tessier 

Tennis - French Open - Roland Garros - Paris - 26/05/2017 - Novak Djokovic of Serbia and his coach Andre Agassi attend a training session. REUTERS/Benoit Tessier 

Tennis - French Open - Roland Garros - Paris - 26/05/2017 - Novak Djokovic of Serbia and his coach Andre Agassi attend a training session. REUTERS/Benoit Tessier 

Tennis - French Open - Roland Garros - Paris - 26/05/2017 - Novak Djokovic of Serbia and his coach Andre Agassi attend a training session. REUTERS/Benoit Tessier 

Tennis - French Open - Roland Garros - Paris - 26/05/2017 - Novak Djokovic of Serbia and his coach Andre Agassi attend a training session. REUTERS/Benoit Tessier 

Tennis - French Open - Roland Garros - Paris - 26/05/2017 - Novak Djokovic of Serbia and his coach Andre Agassi attend a training session. REUTERS/Benoit Tessier 

Tennis - French Open - Roland Garros - Paris - 26/05/2017 - Novak Djokovic of Serbia and his coach Andre Agassi attend a training session. REUTERS/Benoit Tessier 

Tennis - French Open - Roland Garros - Paris - 26/05/2017 - Novak Djokovic of Serbia and his coach Andre Agassi attend a training session. REUTERS/Benoit Tessier 

Tennis - French Open - Roland Garros - Paris - 26/05/2017 - Andre Agassi, coach of Novak Djokovic, attends a training session. REUTERS/Benoit Tessier 

Tennis - French Open - Roland Garros - Paris - 25/05/2017. Novak Djokovic of Serbia and his coach Andre Agassi arrive for a training session. REUTERS/Benoit Tessier 

Tennis - French Open - Roland Garros - Paris - 25/05/2017. Andre Agassi and Darren Cahill during a training session. REUTERS/Benoit Tessier 

Tennis - French Open - Roland Garros - Paris - 25/05/2017. Andre Agassi, coach of Novak Djokovic during a training session. REUTERS/Benoit Tessier 

Tennis - French Open - Roland Garros - Paris - 25/05/2017. Novak Djokovic of Serbia and his coach Andre Agassi during a training session. REUTERS/Benoit Tessier 

Tennis - French Open - Roland Garros - Paris - 25/05/2017. Novak Djokovic of Serbia and his coach Andre Agassi during a training session. REUTERS/Benoit Tessier 

Tennis - French Open - Roland Garros - Paris - 25/05/2017. Novak Djokovic of Serbia and his coach Andre Agassi during a training session. REUTERS/Benoit Tessier 

Tennis - French Open - Roland Garros - Paris - 25/05/2017. Novak Djokovic of Serbia and his coach Andre Agassi during a training session. REUTERS/Benoit Tessier 

Tennis - French Open - Roland Garros - Paris - 25/05/2017. Novak Djokovic of Serbia and his coach Andre Agassi arrive for a training session. REUTERS/Benoit Tessier 

Tennis - French Open - Roland Garros - Paris - 25/05/2017. Novak Djokovic of Serbia and his coach Andre Agassi during a training session. REUTERS/Benoit Tessier 

Tennis - French Open - Roland Garros - Paris - 25/05/2017. Novak Djokovic of Serbia and his coach Andre Agassi during a training session. REUTERS/Benoit Tessier 

Tennis - French Open - Roland Garros - Paris - 25/05/2017. Novak Djokovic of Serbia and his coach Andre Agassi during a training session. REUTERS/Benoit Tessier 

Tennis - French Open - Roland Garros - Paris - 25/05/2017. Novak Djokovic of Serbia and his coach Andre Agassi during a training session. REUTERS/Benoit Tessier 

Tennis - French Open - Roland Garros - Paris - 25/05/2017. Novak Djokovic of Serbia and his coach Andre Agassi during a training session. REUTERS/Benoit Tessier 

Tennis - French Open - Roland Garros - Paris - 25/05/2017. Andre Agassi, coach of Novak Djokovic during a training session. REUTERS/Benoit Tessier 

Tennis - French Open - Roland Garros - Paris - 25/05/2017. Novak Djokovic of Serbia and his coach Andre Agassi during a training session. REUTERS/Benoit Tessier 

Singapore Slammers' Andre Agassi of the U.S. waves to fans after the matches against Manila Mavericks at the International Premier Tennis League (IPTL) in Singapore December 2, 2014. REUTERS/Edgar Su (SINGAPORE - Tags: SPORT TENNIS) 

Singapore Slammers' Andre Agassi of the U.S. hits a return to Manila Mavericks' Mark Philippoussis of Australia during their men's singles match at the International Premier Tennis League (IPTL) in Singapore December 2, 2014. REUTERS/Edgar Su (SINGAPORE - Tags: SPORT TENNIS) 

Singapore Slammers' Andre Agassi of the U.S. hits a return to Manila Mavericks' Mark Philippoussis of Australia during their men's singles match at the International Premier Tennis League (IPTL) in Singapore December 2, 2014. REUTERS/Edgar Su (SINGAPORE - Tags: SPORT TENNIS) 

Tennis star Andre Agassi of the U.S. poses with a basket of bakery products during a photo shoot for an advertisement campaign in Budapest, September 11, 2014. Hungarian fitness guru Norbert Schobert, a former Hungarian policeman who built up a chain of 112 stores selling his low-carbohydrate food, has signed up Agassi to be the face of an expansion into Europe, which he plans to finance with an $8.3 million share offer. Agassi, an eight-times grand slam tennis champion, will be the international face of the brand for three years. Picture taken September 11, 2014. REUTERS/Laszlo Balogh (HUNGARY - Tags: BUSINESS FOOD SPORT TENNIS HEALTH) 

Tennis star Andre Agassi (R) of the U.S. looks on as Hungarian fitness guru Norbert Schobert is handed a basket of bakery products during a photo shoot for an advertisement campaign in Budapest, September 11, 2014. Schobert, a former Hungarian policeman who built up a chain of 112 stores selling his low-carbohydrate food, has signed up Agassi to be the face of an expansion into Europe, which he plans to finance with an $8.3 million share offer. Agassi, an eight-times grand slam tennis champion, will be the international face of the brand for three years. Picture taken September 11, 2014. REUTERS/Laszlo Balogh (HUNGARY - Tags: BUSINESS FOOD SPORT TENNIS HEALTH) 

Tennis star Andre Agassi of the U.S. poses during a photo shoot for an advertisement campaign in Budapest, September 11, 2014. Hungarian fitness guru Norbert Schobert, a former Hungarian policeman who built up a chain of 112 stores selling his low-carbohydrate food, has signed up Agassi to be the face of an expansion into Europe, which he plans to finance with an $8.3 million share offer. Agassi, an eight-times grand slam tennis champion, will be the international face of the brand for three years. Picture taken September 11, 2014. REUTERS/Laszlo Balogh (HUNGARY - Tags: BUSINESS FOOD SPORT TENNIS HEALTH)