World number one Ash Barty was shocked in the first round of the women's singles at the Tokyo Olympics on Sunday.
The Australian was beaten by Sara Sorribes Tormo 6-4, 6-3.
The Spaniard will next play France's Fiona Ferro, who defeated Anastasija Sevastova of Latvia 2-6, 6-4, 6-2, after the biggest win of her career.
Barty commited 55 unforced errors to Sorribes Tormo's 13. The 25-year-old two-time Grand Slam champion, who won the Wimbledon crown earlier this month, was playing in her first Olympic Games.
Her defeat marks the second Olympics in a row where a top seed was beaten in the first round.
At the 2016 Games in Rio de Janeiro, world No. 1 Novak Djokovic was beaten by Argentina's Juan Martin del Potro.
The Serb was untroubled this time, scoring a clinical 6-2, 6-2 win over 139th-ranked Hugo Dellien of Bolivia in his opening match on Saturday.</>
Andy Murray withdraws from singles at Games due to injury
Britain's defending Olympic champion Andy Murray pulled out of the Tokyo 2020 men's singles tournament on Sunday ahead of his first-round match.
The 34-year-old, who had been due to play Canada's Felix Auger-Aliassime, was sidelined by a thigh strain.
Murray has been replaced in the draw by Australian Max Purcell.
The Scot will continue to compete in the men's doubles tournament with Joe Salisbury, Team GB said, the pair having won their opening match on Saturday.
"I am really disappointed at having to withdraw but the medical staff have advised me against playing in both events," a statement from Murray read.
"I have made the difficult decision to withdraw from the singles and focus on playing doubles with Joe."
Murray won Olympic gold on Wimbledon's Centre Court at the London 2012 Games, and defended his title in Rio.
He underwent hip surgery in 2018 and 2019, and missed the Australian Open at the start of this year after contracting COVID-19.