At changeovers, Williams would slink to the sideline, then sit on her green bench with hands clasped, staring straight ahead, expressionless and motionless.
She was far more animated afterward, laughing often while discussing her condition and graciously complimenting the play of Radwanska, a 23-year-old who is coming into her own this season.
"Of course, when I saw the draw, I wasn't very happy, because Venus as a second-round opponent, it's not easy," Radwanska said. "Maybe she just had a bad day here."
While never advancing past the quarterfinals at a Grand Slam tournament, Radwanska has shown signs of being ready for a major breakthrough, with three lesser titles and a tour-high 38 victories in 2012. Of her seven losses, six were against No. 1-ranked Victoria Azarenka.
On an easy day for the top-seeded players, Azarenka breezed into the third round with a 6-1, 6-1 victory over Dinah Pfizenmaier of Germany 6-1, 6-1, while the No. 1 man, Novak Djokovic, extended his Grand Slam winning streak to 23 matches by beating Blaz Kavcic of Slovenia 6-0, 6-4, 6-4.
"Being No. 1 is a difficult job, because everybody want to catch you, everybody want to move you from the spot," said Azarenka, pushed to three sets in the first round. "Nothing is going to come easy just because you're No. 1."
For years, Roger Federer managed to make things look easy at the top. Now No. 3, he went through a bit of a glitch and dropped a set Wednesday before earning his record-breaking 234th Grand Slam match victory, 6-3, 6-2, 6-7 (6), 6-3 against 92nd-ranked Adrian Ungur of Romania.
"I have been around for so long that, even though I expect myself to win, I can still manage to do that," said Federer, on course for a semifinal showdown with Djokovic. "Whereas in the beginning, when you think you're good but you're maybe not that good yet, you get many more surprise losses."
Before rain cut play short in the evening, all 10 seeded men whose matches ended won, including No. 9 Juan Martin del Potro, the 2009 U.S. Open champion, who acknowledged his bandaged left knee is a "constant bother."
Four seeded women lost, including No. 8 Marion Bartoli of France, the runner-up to Williams in the 2007 Wimbledon final, when the American was near the height of her powers.