Serena raises her game to beat Bartoli

By Steve Ginsburg

NEW YORK (Reuters) - Twice former champion Serena Williams advanced to the U.S. Open quarter-finals with a 6-3 6-4 victory over Marion Bartoli on Sunday, raising her game in time for another possible championship run.

The eighth-seeded Williams had 10 aces, landed 73 percent of her first serves and blasted 32 winners against the Wimbledon finalist to play her best match of the tournament.

"Each match I feel like I've gotten better," said Williams. "I'm still not near where I want to be. But I feel like I'm doing better, which is important."

Serena's sister, Venus, also seeking her third Open championship, continued her stellar play with a 6-4 6-2 triumph over French Open finalist Ana Ivanovic.

Venus, who never lost her serve during the 80-minute affair, will play either Austrian Sybille Bammer or third seed Jelena Jankovic of Serbia in the quarters.

On the men's side, Rafael Nadal said he continued to suffer from nagging injuries to both knees but it never showed during a 7-6 6-2 6-1 win over Frenchman Jo-Wilfried Tsonga.

Nadal had only 14 unforced errors and never lost his serve against the 74th-ranked Tsonga.

"It was important for me to win in straight sets," said the second-seeded Spaniard. "For my knees it's better because I can be a little bit more relaxed for the next match."