Earlier in the day, Monaco beat Nantes 2-1 at home to move atop of the league standings on goal difference. Enditem
But just when it appeared as if the race had settled into a predictable rhythm, the Racing Point of Lance Stroll suffered a puncture on lap 43 that sent the Canadian careening off the circuit at high speed.
Williams had to come back from a set and a break down to storm to a 4-6, 6-3, 6-2 win against Bulgaria's Tsvetana Pironkova while Azarenka dropped just one game against 16th seed Elise Mertens of Belgium to seal a spot in the semifinals.
Huesca sprang a minor surprise on their return to the top-flight as they took a point away at Villarreal.
With the runner-up finish, Azarenka said she's proud of herself.
In other matches on Sunday, Atletico Goianiense won 1-0 at Bahia, Atletico Mineiro secured a 2-1 home win against Bragantino and Fortaleza drew 1-1 at Gremio. Enditem
Guoan broke the deadlock in the 30th minute as the ball fell for Zhang Yuning after a series of ricochets, who turned around and finished with a low-strike.
The anarchy in injury time started with a tussle between Argentine pair Dario Benedetto of Marseille and Leandro Paredes of PSG, as the two players were both shown their second yellow cards and were sent off.
So far the only new arrival at Anfield is Kostas Tsimikas, who should provide cover for Andy Robertson at left back, but with plenty of time before the transfer window closes, the club is expected to sign Thiago Alcantara from Bayern Munich to give further options to an already impressive midfield.
"She dug me in a big hole in the first set. I had to climb my way out of there one by one, and I was happy to turn it around, because it wasn't easy. I think it's the daily work I've been doing to find that calm mind and match it with an excited body, because I had to keep moving and bringing the energy. There's no crowd to get energy from, so I had to give it to myself," Azarenka said.
The second Saturday of September every year marks the World First Aid Day.