Kim Clijsters retired injured from her fourth-round match in the ATP & WTA BNP Paribas Open at Indian Wells last night.
There were emphatic wins for Roger Federer and Novak Djokovic in the third round of the men's event.
Second seed Clijsters won the first set 6-3 against 15th seed Marion Bartoli but had to call for her trainer early in the second set due to a nagging shoulder problem. She withdrew soon afterwards, when trailing 3-1 to her French opponent.
"At the end of the Australian Open I was already having some acupuncture from my trainer because I had some pain in that shoulder," two-time Indian Wells champion Clijsters said.
"I told him with the drive volleys and everything higher up, I felt I was struggling a little bit. After Paris [a month ago] I had a break and thought I could rest it well and see how it went here, but it's something I have to pay attention to and don't want to risk."
Federer, second seed in the men's event, had no such worries as he cruised past Argentinian 29th seed Juan Ignacio Chela 6-0 6-2 while third seed Djokovic crushed 31st-seeded Latvian Ernests Gulbis 6-0 6-1.
Next up for Federer will be American wild card Ryan Harrison, who defeated Canada's Milos Raonic 7-6 (7/1) 4-6 6-4, while Djokovic will face 16th seed Viktor Troicki after the Serbian beat Frenchman Michael Llodra 6-3 6-3.
There were also straight-sets third-round victories on Tuesday for seventh seed Tomas Berdych against Thomaz Bellucci, 12th seed Stanislas Wawrinka over Marin Cilic and 18th seed Richard Gasquet against Jurgen Melzer.
In other women's fourth-round encounters, top seed Caroline Wozniacki of Denmark recovered from the loss of the first set to overcome 22nd-seeded Russian Alisa Kleybanova 2-6 6-3 6-1.
Nineteenth seed Ana Ivanovic stunned fellow Serbian Jelena Jankovic, seeded six, 6-4 6-2, while 10th seed Shahar Peer of Israel dumped fifth-seeded Italian Francesca Schiavone 6-4 3-6 7-6 (7/3).
There were also wins for eighth seed Victoria Azarenka and 23rd seed Yanina Wickmayer at the expense of Agnieszka Radwanska and Dominika Cibulkova respectively.
In the evening action, eighth seed Andy Roddick set up a fourth-round meeting with Gasquet by posting a 7-5 6-2 victory in his all-American battle with 30th seed John Isner.
In the women's fourth round, 16th seed Maria Sharapova breezed past fellow Russian Dinara Safina with the minimum fuss - 6-2 6-0.
Next up for Sharapova will be a quarter-final meeting with China's Shuai Peng, who came through a testing encounter with 18th seed Nadia Petrova of Russia 6-4 5-7 6-3.