Ash Barty has lamented a "loose and erratic" effort after she fell flat in a shock first-round Toyko Olympic loss to unheralded Spaniard Sara Sorribes Tormo.
The world No.48 beat world No.1 and newly crowned Wimbledon champion Barty 6-4 6-3 in the biggest shock of the Games to date as the Australian fell apart in the blistering Tokyo heat.
Barty made a staggering 55 unforced errors to the Spaniard's 13, the Queenslander desperately out of sorts 15 days after clinching her second grand slam title.
"It was a tough day. A disappointing day. I can't lie about that," she told the Seven Network.
"I can't hide behind that fact that I wanted to do really well here. Today wasn't my day.
"Just loose. I knew I wanted to try to take the match on (and) it would be a fine line of not pushing too hard and not getting in the patterns I didn't want to get stuck in.
"(I was) too erratic."
The scorching, humid conditions had men's No.1 Novak Djokovic calling for matches to begin later in the day after his first-round victory on Saturday.
Although the schedule remained the same on Sunday, a concession was made with longer breaks at changes of ends as part of the extreme weather policy.
"It's brutal, like an Australian summer (but) I enjoy the heat and love playing out here in these conditions. Wasn't meant to be," Barty said.
It leaves Barty's medal hopes resting on the doubles, having advanced to the second round with Storm Sanders after a win on Saturday.