Serena Williams was left disappointed but paid tribute to Elina Svitolina after a surprise loss in the women's singles at Rio 2016.
The American reigning champion had 37 unforced errors in a 6-4 6-3 defeat against Ukraine's Svitolina in the third round on Tuesday.
Williams, a 22-time grand-slam champion, praised Svitolina, who she had beaten in their four previous meetings.
"It's obviously disappointing, but she played really well and I think the better player today won," she said.
"I can't wait for the next time and I know next time it's going to be a really good match. I'll look forward to it."
The Rio Games marked Williams' fourth - and surely last - Olympics, and she has four gold medals in her trophy cabinet.
Already out of the doubles with sister Venus, Serena said getting to Brazil had been an achievement.
"It was a career opportunity. It didn't work out the way I wanted to, but at least I was able to make it to Rio. That was one of my goals," she said.
"It was awesome. It was fun. But it's over now."
-- ITF Olympic Tennis (@OlympicsTennis) August 9, 2016
Williams fell apart in the second set against Svitolina, including serving five double faults in a single game.
Svitolina said: "It happens sometimes with her serve, but she can do also four aces in a row. You need to expect the unexpected.
"I was staying in the moment, I didn't really think about it, I was trying to be focused because there can be two double faults and then one ace, so it's tough to really think something different than the next point."
The 21-year-old, ranked 20th in the world, was predictably thrilled with her win as she set up a quarter-final meeting with Petra Kvitova.
"It's unreal. It's just the perfect moment. To beat her at the Olympics is extremely special for me," Svitolina said.
"I was expecting that I could play well. Just push to her limits. Obviously she was not playing well today, but in some moments she was serving really well and playing some great shots.
"I expected it was going to be up and down and I think I played really well today. I was just waiting for my opportunity."