Sister Serena stays on course at the US Open

Three weeks before her 19th birthday, defending champion Serena Williams stayed on course at the U.S. Open, drilling 12 aces in a 6-4, 6-2 rubout of Giulia Casoni 6-4, 6-2.

Three weeks before her 19th birthday, defending champion Serena Williams stayed on course at the U.S. Open, drilling 12 aces in a 6-4, 6-2 rubout of Giulia Casoni 6-4, 6-2.

Saturday's win got her through to the round of 16 and kept alive the possibility that younger sister Serena could meet older sister Venus in an all-Williams final next Saturday.

In an Open that lost its top two men's seeds in the first three days, the Williams sisters offer the chance of injecting some real electricity into America's Grand Slam.

After Serena finished off Casoni, a reporter suggested that Venus was the favourite as the Open turns into its second week.

"Is she?" Serena said cooly.

The message was clear. Don't forget about the defending champion.

"Right now, my game can compete with anyone," she said. "It doesn't matter who I play. I'm definitely a better player. Last year, I don't see how I won to be honest, compared with where I am now.

"Now, overall, I'm just a better player. The Serena of today could definitely beat the Serena of last year, although it would be a tough match because any Serena is hard to beat on any given day."

Next up for Williams in the round of 16 is Jelena Dokic, who has been riding her own emotional roller coaster at the Open after her father was barred from the tournament for disruptive behaviour in the players lounge.

"It's good that I get a tough match," Serena said of Casoni. "At first, I thought I wanted an easy match in every round. But after Wimbledon, I realised I want tough ones."

It was at Wimbledon that Serena was forced into that semifinal showdown with her sister, who went on to win the championship.

A month later, Serena bounced back from that loss to defeat Martina Hingis in the semifinals and Lindsay Davenport in the finals to win at Los Angeles. Then there was a loss in the finals to Hingis in the Canadian Open, her last warmup before the Open.

Williams carried the No. 5 seed into the season's final Grand Slam. She missed 2 1/2 months with a knee injury and returned to reach the semifinals at Wimbledon. That loss has stayed with her and now she has an opportunity to get even with her sister.

"I look forward to that moment," she said. "There are a couple of roadblocks. I've got to get by those first."

Serena recalled making a sea of unforced errors here a year ago en route to the championship. That, she said, was then. This is now.

"I've really cut that Serena out of me," she said. "I don't do that anymore."

There were 18 unforced errors against Casoni but Serena was never in serious trouble. She converted 24 of 28 first serve points and four of five break point opportunities.

She had the only break of the first set and took control of the match in the second, finishing Casoni off on match point with a slam at the net. Then she blew kisses to the crowd.

"I'm really competitive," Williams said. "I like to win a lot. When I'm able to hold up the trophy at the end of a tournament, that's a great feeling for me."

Even if it means Venus goes home empty-handed.