NEW YORK It didn't take long for Serena Williams to show her fourth-round opponent at the U.S. Open where things were headed.
"The first point of the whole match," 82nd-ranked Andrea Hlavackova of the Czech Republic explained, "when I served, and she returned, like, a 100-mph forehand return, I was like, 'OK, I know who I'm playing. You don't have to prove it to me. I know.' "
Monday's match was less than 15 seconds old. It might as well have been over.
Dominant from the moment she ripped that return of an 88-mph second serve, forcing Hlavackova into an out-of-control backhand that sailed well long, to the moment she powered a 116-mph service winner on the last point, Williams extended her 21/2-month stretch of excellence with a 6-0, 6-0 victory to get to the quarterfinals at Flushing Meadows.
Those two big zeros pretty much tell the story; it's the fifth time in her career Williams won with what's commonly called a "double bagel." Some other impressive numbers: Williams won 60 of 89 points, built a 31-9 advantage in winners and improved to 23-1 since losing in the first round of the French Open. That run includes singles and doubles titles at Wimbledon and the London Olympics.
No. 10 Sara Errani, an Italian who was the runner-up to Maria Sharapova at the French Open, got past No. 6 Angelique Kerber of Germany 7-6 (5), 6-3.
Italy's Roberta Vinci, reaching her first singles quarterfinal in 32 career Grand Slam tournaments, stunned No. 2 Agnieszka Radwanska 6-1, 6-4. Radwanska could have moved up to No. 1 in the WTA rankings by reaching next weekend's final.
Top-seeded Roger Federer got some extra rest because his fourth-round opponent, 23rd-seeded Mardy Fish of the United States, withdrew hours before their scheduled match for precautionary reasons, citing medical advice.
The man Federer beat in July's Wimbledon final and lost to in August's Olympic final, Andy Murray, muted 15th-seeded Milos Ranoic's big serve and won 6-4, 6-4, 6-2 Monday night to reach an eighth consecutive major quarterfinal.
Fish, 30, missed about 21/2 months this season because of an accelerated heartbeat and had a medical procedure in May. The walkover left soon-to-retire 2003 U.S. Open champion Andy Roddick, who plays 2009 champ Juan Martin del Potro in the fourth round tonight, as the last American man in the field.
Note Rafael Nadal has a partially torn patella tendon in his left knee and will be sidelined for at least the next two months, including Spain's upcoming Davis Cup semifinal against the United States.