JOIN USZheng Jie from China survived a three-hour match against former World No.1 Williams 6-3, 2-6, 7-6 (7-5) to advance to the US Open tennis third round.
With the win Wednesday, Zheng's equalled her personal best record at US Open. She reached US Open last 32 in 2008, 2009 and 2012, reports Xinhua.
The match was scheduled to start at 1 pm, but was postponed to 5:20pm because of the rain delay.
"According to the rules, we have to follow the decision of the organizers," said the 30-year-old Zheng.
"It's tough because I have to keep the energy and focus. I was so happy to beat her because she was so tough and in United States many people support her."
Williams held serve to start the game 1-0, and Zheng responded with a break in the third game, keeping serve to take a 3-1 lead.
Neither player was able to break until the ninth game, in which William made sent a couple of forehand strokes long to allow three set points for Zheng, who seized the chance to end the first set 6-3.
Williams found her rhythm in the second set, establishing a 3-1 lead. The fifth game became the decisive one in the second set, which lasted for more than ten minutes.
Williams managed to accomplish a break after seven deuces, finishing the second set 6-2.
"Venus is still a dangerous player, and she has the big serve," Zheng said.
"You can see from the second set that if I don't play aggressively she can quickly come back. "
The decisive set seemed to went in Zheng's way when the score got to 4-1, but Williams made an important break in the seventh game to catch up. The two players leveled until 6-6 to enter the tie-break.
In the tie-break, Zheng made a 4-1 lead again, and Williams caught back to 4-4 again. However, the winner of seven Grand Slams netted a forehand stroke when the score got to 5-5, handing Zheng a match point. Zheng made full use of the match points, wrapping up the victory after Williams sent a forehand stroke wide.
"It was amazing," said Zheng after the match.
"I still feel tight because in the tiebreak the points are very close."
Zheng would next face No. 18 seed Suarez Navarro from Spain.
"She's played so great these two years, I had practiced and played several matches with her in Cincinnati. She was so good," Zheng said of her next rival.