After rain wreaked havoc in New York over the last two days, the women finally returned to the courts at the USTA Billie Jean King National Tennis Center for the first time since Monday.
The 28th-seeded Williams handled 17th-seeded Russian Anastasia Pavlyuchenkova 7-5, 6-1 at Arthur Ashe Stadium, as the bout came to a close when the American great fired her seventh ace of the afternoon.
Williams advanced in 1 hour, 19 minutes with the help of six aces among her 26 winners. The powerful star broke the young Russian six times and Pavlyuchenkova also piled up 31 unforced errors en route to the predictable defeat.
The 29-year-old Williams is a 13-time major titlist, including a trio of U.S. Open victories. She also posted a runner-up finish to her older sister Venus here in Flushing back in 2001.
Serena is currently riding a 17-match overall winning streak, all on hardcourts, which includes titles in Stanford and Toronto.
If Serena can title here this week she would pocket $2.8 million, which would include a $1 million bonus for winning the U.S. Open Series this summer.
She'll now appear in her sixth career U.S. Open semifinal (4-1).
Meanwhile, the ninth-seeded Stosur beat the second-seeded Russian Zvonareva for an eighth straight time, as the Aussie posted a comprehensive 6-3, 6-3 victory in 67 minutes on the Grandstand court. Stosur fired 25 winners, compared to only nine for the Russian on Day 11, and Zvonareva was unable to break her big-serving Aussie counterpart.
Stosur was last year's French Open runner-up, while Zvonareva lost in last year's U.S. Open and Wimbledon finals. Zvonareva gave way to Belgian star Kim Clijsters in a lopsided finale last year in Flushing.
The 27-year-old Stosur will now appear in her third career Grand Slam semifinal and her first-ever U.S. Open semi.