PARIS -- When Serena Williams had won the final point Sunday, she paused behind the baseline to urge herself on with one last fist pump.
"Come on!" she shouted, as if her work wasn't done -- which it isn't.
Williams earned a berth in the French Open quarterfinals and extended her career-best winning streak to 28 matches by beating No. 15-seeded Roberta Vinci 6-1, 6-3.
It was her toughest test of the first week, but she swept the last 10 points and has lost only 10 games through four rounds.
"I just want every point," she said. "Every match I'm really focused for the whole period of time. I really want it every match."
The 15-time Grand Slam champion next plays 2009 French Open winner Svetlana Kuznetsova. The Russian, ranked 39th but rejuvenated this year, beat No. 8-seeded Angelique Kerber 6-4, 4-6, 6-3.
With another victory, Williams would earn her first berth in a French Open semifinal since 2003. She won her lone Roland Garros title in 2002.
The three other remaining Americans play Monday. Four U.S. women reached the fourth round, the most at the French Open since 2004.
Tommy Robredo became the first man since 1927 to overcome a two-set deficit in three consecutive matches at a major event. Seeded 32nd, he beat fellow Spaniard Nicolas Almagro 6-7 (5), 3-6, 6-4, 6-4, 6-4.
The 31-year-old Robredo will next play another Spaniard, David Ferrer, who reached the quarterfinals for the sixth straight Grand Slam by beating Kevin Anderson 6-3, 6-1, 6-1.
No. 6 Jo-Wilfried Tsonga, a threat to become the first Frenchman in 30 years to win Roland Garros, beat unseeded Viktor Troicki 6-3, 6-3, 6-3.
Vinci tried everything to get Williams off balance. The 5-foot-4 Italian played serve and volley, attempted to chip and charge and mixed the pace of her groundstrokes, including an occasional drop shot.
"She played really smart," Williams said. "I knew how she was going to play. Some of the things she did I definitely expected, and I just had to come up with an answer."
Williams answered forcefully, whacking second serves harder than Vinci's first serves, and her persistent power proved the difference.
"I don't want to say it was a one-sided match, but it basically was," Vinci said. "She hits hard, and you can't tell where she's going to hit it."
Serving in the opening game of the second set, Williams fell behind love-30, as if trying to make it a fair fight. She then hit an ace, kissed a forehand winner off a line, won the next point with another booming groundstroke and closed out the game with a drop-shot winner.
The rout left Vinci regretting the luck of the draw.
"It's a shame I had to face Williams here," Vinci said. "She's the strongest player by far."
Williams improved to 20-0 this year on clay. Since losing in the first round a year ago at Roland Garros, she's 71-3, including titles at Wimbledon, the U.S. Open, the London Olympics and the season-ending WTA Championships.
Williams first reached the quarterfinals at Roland Garros in 2001, when she was 19. Now she's 31 and the oldest player in the top 10.
"She's the best in the world," said Kuznetsova, who is 2-6 against her. "She has been playing unbelievable tennis. But I believe that I have game and my good days as well. Let's cross fingers I will have a good day."
Kuznetsova won their most recent meeting, in the 2009 quarterfinals at Roland Garros, and went on to the title.
The Russian has now reached the final eight in back-to-back major tournaments for the first time since that year. She made the quarterfinals at the Australian Open in January before losing to eventual champion Victoria Azarenka.
"Grand Slams always bring the best out of me," Kuznetsova said. "It just comes naturally. Here it's the French Open -- it says everything."
Kuznetsova whacked a forehand winner on match point, then let out a jubilant scream. She improved to 12-2 this year in three-set matches, and her winning percentage of .820 (41-9) at Roland Garros is the best among active players.
Robredo not only overcame a two-set deficit for the sixth time in his career, but he rallied from a break down in both the fourth and fifth sets. He collapsed to the clay and fought back tears after closing out the 4½-hour victory.
Ranked 470th a year ago, Robredo missed Roland Garros in 2011 and 2012 but is now in the quarterfinals for the fifth time.
While Robredo keeps going the distance, the No. 4-seeded Ferrer has won four matches without dropping a set. He's a four-time major semifinalist, including at Roland Garros last year, but has yet to reach a final.
Against the No. 23-seeded Anderson, Ferrer converted 6 of 17 break-point chances, held every service game and committed only 11 unforced errors to 41 for the South African.