Garbine Muguruza's chances of winning her maiden grand slam title -- and achieving the rare feat of beating Serena Williams twice in three years at Roland Garros -- may well depend on which version of the world number one turns up on Sunday.
Tournament favourite Serena Williams withdrew from the Italian Open on Saturday with a lower back injury, the WTA said.
Serena Williams has pulled out of the US Open because she is still recovering from surgery on her right foot, the American world number one said on Friday. Williams, who won her 13th Grand Slam at Wimbledon earlier this year, cut her foot on broken glass at a restaurant in July and has not played since.
Serena Williams must stop giving opponents head starts if she is to come anywhere near emulating last season's feat of winning three of the year's four Grand Slams, according to former World No 1 Chris Evert.
Also making it to the last eight were Svetlana Kuznetsova and Czech teenager Nicole Vaidisova.
Victoria Azarenka and Serena Williams will square off for the Madrid Open title after the current and former World No. 1's swept into the final with a minimum of fuss on Saturday.
Bollettieri founded the Nick Bollettieri Tennis Academy in 1978. It was bought by the International Management Group in 1987.
Serena Williams marked her first European appearance of the season with victory on the Madrid Open's striking blue clay courts on Monday, but her sister Venus crashed out in the second round.
Under the lights on the stadium court, Williams smashed 39 winners to defeat Azarenka 7-5, 6-3 in a rematch of the 2016 final, which the Belarusian won.
Belgium's Yanina Wickmayer labored past Kai-Chen Chang 7-5, 2-6, 7-5 in the first round of the Stanford Classic on Monday but all eyes will be on Wimbledon champion Serena Williams who begins her title defense on Wednesday.
American Serena Williams powered her way to a fifth Wimbledon singles title with an explosive start and a cool finish after a mid-match meltdown to beat Poland's Agnieszka Radwanska 6-1, 5-7, 6-2 on Saturday.
Serena Williams roared into a her seventh Wimbledon singles final with a 6-3, 7-6 victory over Victoria Azarenka on Thursday. She will face Poland's Agnieszka Radwanska in Saturday's final.
Serena Williams continued her inconsistent play but rolled into the third round of the U.S. Open with a 7-5 6-2 victory over Italian Maria Elena Camerin on Wednesday.
A subdued Serena Williams recovered from a sluggish start to beat China's Zheng Jie 6-7, 6-2, 9-7 in a marathon Wimbledon third-round match on Saturday.
American Serena Williams won her fourth Wimbledon singles title on Saturday when she crushed Russian 21st seed Vera Zvonareva 6-3, 6-2 in the final at the All England Club.
Defending champion Serena Williams withstood stiff early resistance from unseeded Czech Petra Kvitova before winning 7-6, 6-2 to reach her sixth Wimbledon singles final on Thursday. She will meet Vera Zvonareva, who survived an early wobble before scoring a 3-6, 6-3, 6-2 victory over unseeded Bulgarian Tsvetana Pironkova in the other semi-final.
A display of violent hitting from Robin Soderling on Saturday showed why it is always unwise to ignore a Swede at the business end of Wimbledon as Serena Williams gave herself a 'must do better' report as she eased into round four.
France's Alize Cornet beat a despondent Serena Williams 6-4, 6-4 in the semi-finals of the Dubai Championships on Friday in what the world number 26 described as the biggest win of her career.
Pre-tournament favourite and 13-times Grand Slam champion Serena Williams suffered her first ever opening round defeat at a Grand Slam when she was beaten 4-6, 7-6, 6-3 by Frenchwoman Virginie Razzano at the French Open on Tuesday.
Serena Williams easily won her eagerly-awaited clash with Sloane Stephens at the US Open on Sunday as normal service resumed at the last Grand Slam of year.
World No 1 Williams, 33, could not practise on Friday, still suffering from an illness that left her coughing and spluttering during her three-set semi-final win over Swiss Timea Bacsinszky.