Former World No. 1 Venus Williams, 36 years old, fought a tough first round battle against Belgium’s Kristen Flipkens. After three tight sets, the American fell hard, 6-4, 3-6, 7-6.

Williams – a seven-time Grand Slam champion – was neck-and-neck with Flipkens in the first set, but managed to overcome her opponent. She then surrendered the second set in a fairly decisive fashion.
The current World No. 6 seemed to take control in the third set with a 4-1 lead, but experienced difficulty closing out the match. Soon enough, Flipkens evened the score.
Finally, the two players swung in out in a tense third set tiebreak. Flipkens emerged the victor, 4-6, 6-3, 7-6.
She fell on the ground, astonished. Flipkens missed the London 2012 Games due to a blood clot in her thigh.

On the whole, the Americans were a mixed bag. The men’s side – not considered as strong as the country’s women players – saw some significant losses. World No. 25/14th-seeded Jack Sock of Kansas, arguably the U.S.’ best medal hopes in men’s singles, fell flat in the first round. He lost in straight sets to Japan’s World No. 125/unseeded Taro Daniel of Japan.

Meanwhile, unseeded Brian Baker – who made it onto the U.S.’ Olympic team due to a “protected ranking” – lost in a tight three sets to Japan’s Yuichi Sugita.

American No. 12 seed Steve Johnson handily defeated unseeded Barbados’ Darian King.

Rising U.S. star Madison Keys faced a tough opponent in Montenegro’s Danka Kovinic, but ultimately defeated her in straight sets, 6-3, 6-3. Keys advanced to the top ten world rankings for the first time earlier this year.

But Sloane Stephens – another U.S. up-and-comer – lost by the same score to Canadian Eugenie Bouchard, who’s experiencing something of a comeback following injury.

A busy day one of tennis competition at the Rio Games (25 streamed matches overall across singles and doubles, plus more on the outer courts) was bound to include some upsets. But almost all the favorites were in danger of early round exits at some point today, with medal favorite Aga Radwanska of Poland also losing in the first round.

Radwanska took to court 1 in the early afternoon and was ousted from the tournament approximately an hour later. The Polish World No. 5 fell to the China’s World No. 64 Zheng Saisai in straight sets, 6-4, 7-5.

It reportedly took Radwanska 55 hours of travel to make it to Rio, following a repeatedly delayed flight out of Canada. She finally arrived in Rio on Wednesday evening and apparently developed an illness shortly thereafter.

Furious at her circumstances, the generally mild-mannered Radwanska smashed her racket after the uncharacteristic premature loss.

Other big name losses: Italy’s Roberta Vinci (seeded sixth), who famously denied Serena Williams the calendar Grand Slam at last year’s US Open, and Switzerland’s Timea Bacsinszky (seeded twelfth).

Tomorrow’s schedule is chock-full of tennis superstars, including (on the men’s side) World No. 1 Novak Djokovic (SRB), World No. 2 Andy Murray (GBR) and World No. 3 Rafael Nadal (ESP). On the women’s side, World No. 1 Serena Williams (USA), World No. 2 Angelique Kerber (GER) and World No. 3 Garbine Muguruza (ESP) will play their first-round matches.

And Venus fans, don’t fret – she’ll be back on court tomorrow alongside sister Serena, defending her doubles gold medal.