"Sometimes it's good to play first, even when I have to wake up really early,'' Radwanska said, referring to the rain.
Other early winners were 32nd-seeded Anastasia Pavlyuchenkova and, on the men's side, one-time top-10 player Marcos Baghdatis.
With the storm bearing down, video monitors around the Billie Jean King Tennis Center warned fans to seek shelter and avoid trees because of potential lightning, though thousands of ticketholders were milling about without much concern for severe weather.
Many are used to this scene.
The season's last Grand Slam tournament has finished a day late for five straight years because of rain delays.
This year, the U.S. Tennis Association announced plans to build a roof over Arthur Ashe Stadium as part of a renovation project that will cost $550 million. The roof could be ready by 2016, or 2017 at the latest.
Even that wouldn't have alleviated a first-week logjam the likes of which the tournament faced Wednesday, with a full slate of matches in singles along with men's, women's and mixed doubles.
Among those on the schedule later Wednesday were defending women's champion Serena Williams and sister Venus; 2009 men's champion Juan Martin del Potro and defending champion Andy Murray, whose first-round match against Michael Llodra was set for Arthur Ashe Stadium at night.
During a brief halt to the storm, del Potro made it onto the court, earned an early break against Guillermo Garcia-Lopez of Spain, then had to go back to the locker room when the rain returned. Next door, at Armstrong Stadium, Venus Williams played two points against Zheng Jie, then went inside again.
Li was among the few who could plan on watching those matches from her hotel room.
"I'm happy,'' she said. "Because at least I'm done with my job for the day.''
- AP