Australia's Ashleigh Barty returns the ball to Romania's Simona Halep during their WTA Madrid Open round of 8 tennis match at the Caja Magica in Madrid on May 9, 2019. Two-time champion Simona Halep overcame Ashleigh Barty 7-5, 7-5 to reach her fourth Madrid Open semi-final today. Romania's third seed and former number one will next play the winner from top seed Naomi Osaka and on-form Swiss Belinda Bencic. (Photo by GABRIEL BOUYS / AFP via Getty Images)

Romania's Simona Halep returns the ball to Australia's Ashleigh Barty during their WTA Madrid Open round of 8 tennis match at the Caja Magica in Madrid on May 9, 2019. Two-time champion Simona Halep overcame Ashleigh Barty 7-5, 7-5 to reach her fourth Madrid Open semi-final today. Romania's third seed and former number one will next play the winner from top seed Naomi Osaka and on-form Swiss Belinda Bencic. (Photo by GABRIEL BOUYS / AFP via Getty Images)

Real Madrid's Costa Rican goalkeeper Keylor Navas (L), his wife Andrea Salas and Atletico Madrid's Spanish midfielder Saul Niguez (R) attend the ATP Madrid Open tennis tournament at the Caja Magica in Madrid on May 8, 2019. (Photo by Pierre-Philippe MARCOU / AFP via Getty Images)

Spanish centre-right Ciudadanos (Citizens) party leader Albert Rivera (C) attends the ATP Madrid Open tennis tournament at the Caja Magica in Madrid on May 8, 2019. (Photo by Pierre-Philippe MARCOU / AFP via Getty Images)

Romania's Simona Halep returns the ball to Australia's Ashleigh Barty during their WTA Madrid Open round of 8 tennis match at the Caja Magica in Madrid on May 9, 2019. Two-time champion Simona Halep overcame Ashleigh Barty 7-5, 7-5 to reach her fourth Madrid Open semi-final today. Romania's third seed and former number one will next play the winner from top seed Naomi Osaka and on-form Swiss Belinda Bencic. (Photo by GABRIEL BOUYS / AFP via Getty Images)

Atletico de Madrid's Slovenian goalkeeper Jan Oblak (L) attends the ATP Madrid Open tennis tournament at the Caja Magica in Madrid on May 8, 2019. (Photo by Pierre-Philippe MARCOU / AFP via Getty Images)

Former chief executive of the Formula One Group British Bernie Ecclestone (L) and Romanian businessman Ion Tiriac attend the ATP Madrid Open tennis tournament at the Caja Magica in Madrid on May 8, 2019. (Photo by Pierre-Philippe MARCOU / AFP via Getty Images)

Spain's Rafael Nadal celebrates after beating Canada's Felix Auger Aliassime in their ATP Madrid Open tennis match at the Caja Magica in Madrid on May 8, 2019. (Photo by Pierre-Philippe MARCOU / AFP via Getty Images)