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.
Thursday saw some rumors in the press that the player was considering a U-turn to see out the remaining year of his contract, but Jorge Messi's communique implies there is no climb-down from the family.
National teammate Zhang Yaoguang finished second at 8.23m, followed by Asian Games champion Wang Jianan at 8.08m.
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.
Behind the top three, Norris took fourth ahead of an out of sorts Bottas, who looked off the pace all day and appeared to suffer with handling and overheating problems.
Damjan Bohar scored the only goal for Slovenia in the 28th minute.
"There's no past Grand Slam champions left in the draw," said fifth seed Alexander Zverev from Germany, who made light work of Spain's Alejandro Davidovich 6-2, 6-2, 6-1 in another fourth round match.
Also on Sunday, Wales edged Bulgaria 1-0 to top the second-tier Group B4, while Ireland lost 1-0 at home to Finland.
Defender Mohammad Reza Khanzadeh, midfielders Ashkan Dejagah and Akbar Imani scored for Tractor in the first half.
Defending champion Egan Bernal also arrived with the leading group and was able to improve his overall ranking to second place.
"I'm happy for the mentality, the performance, the boys really played brilliantly," Mancini told Italian broadcaster Rai.