Tokyo: Top-ranked Ash Barty and two-time defending Olympic singles champion Andy Murray are turning their attention to doubles. That's not necessarily what they wanted, though.
Barty was upset by 48th-ranked Spanish opponent Sara Sorribes Tormo 6-4, 6-3 in the first round of the singles tournament at the Tokyo Games on Sunday. That came shortly after Murray withdrew from singles because of a right quad strain.
Both still remain in the doubles competition.
Barty won with Australian partner Storm Sanders on Saturday while Murray and British partner Joe Salisbury beat the second-seeded French team of Pierre-Hughes Herbert and Nicolas Mahut.
Barty's singles defeat came 15 days after she won Wimbledon for her second Grand Slam title.
She struggled with a whopping 55 unforced errors to Sorribes Tormo's 13 and got in only 54% of her first serves compared to her opponent's 83%.
Murray pulled out shortly ahead of his scheduled opener against ninth-seeded Felix Auger-Aliassime of Canada on Center Court.
"I am really disappointed at having to withdraw but the medical staff have advised me against playing in both events, so I have made the difficult decision to withdraw from the singles and focus on playing doubles with Joe," Murray said.
It's the latest setback for the 34-year-old Murray after only recently returning to the tour from a three-month absence because of a groin problem. He has also had serious issues with a bad hip that wound up requiring two operations.
Murray has a total of three Olympic medals. He also won a silver in mixed doubles at the 2012 London Games with Laura Robson.
Max Purcell of Australia was to play Auger-Aliassime instead.
Also coming up was second-ranked Naomi Osaka against 52nd-ranked Zheng Saisai of China.
It's Osaka's first match in nearly two months " since she withdrew from the French Open and sat out Wimbledon to take a mental health break, revealing she has dealt with depression.
Osaka's match was originally scheduled to open the tennis tournament on Saturday but then was moved to Sunday before she lit the cauldron in Friday's opening ceremony.
Heat and humidity were issues again with the temperature 91 degrees F (33 degrees C) at Ariake Tennis Park, with the heat index making it feel like 99 degrees F (37 degrees C).
Also, Wimbledon finalist Karolina Pliskova of the Czech Republic beat Alize Cornet of France 6-1, 6-3.