Kosgei was later disqualified for stepping onto the infield in the closing stages.
According to relevant anti-virus rules, any player who leaves the bubble has to pass a virus test and go through medical observation in isolation before returning, the paper said.
Stephens went up a double break to carve out a 5-2 lead and served out the opening set in just 38 minutes. But Williams began to raise her game and served much better in the second set, lifting her first-serve percentage from 50 to 76 percent. By breaking twice, Williams won the second set to level the match.
The remainder of the match was controversial after Gao Lin was shown his fourth yellow card of the season in the 71st minute after complaining to the referee. The Chinese international is set to miss Shenzhen's next match against his former club Guangzhou Evergrande next Wednesday.
In another third round clash, Australian Open champion Kenin had to weather a barrage of 35 winners coming from Jabeur's racquet, and stayed solid to break the Tunisian's serve three times, fighting her way to a 7-6 (4), 6-3 victory.
"I corresponded with the German Football Association DFB about Piatek's case. They ensured that they will try their best to let the player avoid the quarantine. A week ago we had a meeting with UEFA. We heard that the national federations should contact their governments to talk about the safety rules in those situations," added Kwiatkowski.
Williams will take on Bulgaria's Tsvetana Pironkova, who overcame Alize Cornet of France 6-4, 6-7 (5), 6-3 in another round of 16 match.
Elsewhere, fifth seed Alexander Zverev of Germany beat Frenchman Adrian Mannarino 6-7 (4), 6-4, 6-2, 6-2 to advance, while fourth seed Stefanos Tsitsipas of Greece was upset by Croatia's Borna Coric in a five-set thriller.
ACCRA, Sept. 8 (Xinhua) -- Ghana has invited some 40 players into the camp of the national under-17 team, the Black Starlets, the Ghana Football Association (GFA) announced here on Tuesday.
"One, it will be good economically. But also it will make sense in a context where we might still face a COVID situation. To what extent we don't know, but at least we'll have thought about what it takes to deliver an event like the Games in such an environment."
Osaka lost all three of her previous matches against Rogers, but this time she turned the tables and needed just one hour and 20 minutes to triumph.