Venus Williams of the US hits a return to Maria Jose Martinez Sanchez of Spain at the Wimbledon tennis championships in London June 24, 2011. [Photo/Agencies]

LONDON - Serena and Venus Williams loom large over the women's draw as the 125th Wimbledon championships rolls into its second week.

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No surprise there considering the American sisters have dominated the grasscourt slam for the last decade, only this time their progress to Monday's last 16 has been followed a little more intently after both returned in the nick of time from long lay-offs and with doubts about their condition.

In reigning champion Serena's case, her three wins so far have been nothing short of remarkable.

The 29-year-old powerhouse spent almost the whole year since winning her fourth Wimbledon title battling to save her career, first from a lacerated foot tendon caused by a freakish accident in a Munich restaurant and then, more worryingly, having a brush with death when blood clots were found in her lungs in February.

Yet despite minimal match practice and showing signs of rustiness, the 13-times grand slam champion survived the first week of the tournament unscathed.

What is more, there are ominous signs that her heavy weaponry is about to be unleashed as she prepares to take on ninth seeded Frenchwoman Marion Bartoli, the 2007 runner-up.

Her victory over Maria Kirilenko on Saturday was her most emphatic this year after being taken to three sets in the first two rounds and she will always be a contender thanks to one of the best serves ever seen in women's tennis.

"I saw it a little bit today in the second set. I was like, where have you been?" seventh seed Williams said of her howitzer delivery. "He was at a party or something. But he's back.

"Marion's good and she moves fast. She does everything really good. She's actually a really, really good returner, so I'm really gonna have to make sure that I'm in there serving well on Monday."

 

Serena Williams of the US hits a return to Maria Kirilenko of Russia at the Wimbledon tennis championships in London June 25, 2011. [Photo/Agencies]

Best Game

Five-times champion Venus, who also returned at the Eastbourne warm-up event after a five-month absence with a hip problem, will have revenge on her mind when she plays Bulgaria's Tsvetana Pironkova on Centre Court.

Pironkova knocked her out at the quarter-final stage last year but the 31-year-old Williams is promising a much-improved performance this time.

"Last year, unfortunately I didn't play that well.  On a competitive level, I don't feel I competed well. Regardless of how I play, I know I'll be competing this time," the 23rd seed said. "I'm ready to bring my best game and my best competition."

Russian fifth seed Maria Sharapova is the only other woman in the last 16 with a grand slam-winning pedigree and, along with world number one Caroline Wozniacki and Czech left-hander Petra Kvitova, looks the biggest threat to the Williams sisters who are careering towards a fifth family final at Wimbledon.

Sharapova faces Peng Shuai of China while Wozniacki, who has made smooth progress through the draw so far, faces Dominika Cibulkova of Slovakia.

Eighth seed Kvitova takes on Belgium's Yanina Wickmayer.