Wimbledon tennis: Nadal faces del Potro, Williams sisters eye final

LONDON: Defending champion Rafael Nadal's Wimbledon campaign runs into the imposing 1.98m (6ft 6ins) figure of dangerman Juan Martin del Potro Monday while the rejuvenated Williams sisters eye another final date.

World number one Nadal, the 2008 and 2010 winner, has the toughest-looking clash of the fourth round when he tackles Argentine del Potro, the man who blew him off court in the US Open semi-finals in 2009 for the loss of just six games.

But the Spaniard, fresh from his sixth French Open title, can take heart from his form so far at Wimbledon where he has yet to drop a set.

Del Potro, by contrast, had to play on all six days of the first week as heavy rain played havoc with the scheduling.

Del Potro insists all the pressure will be on Nadal in their eagerly-awaited fourth round clash.

Second seed Novak Djokovic was given a stern workout in his third round encounter by Cypriot Marcos Baghdatis on Saturday where he dropped his first set of the competition.

Djokovic, beaten just once all year, faces French left-hander Michael Llodra.

Six-time champion Roger Federer faces Russia's Mikhail Youzhny who he has beaten 10 times out of 10.

Federer, chasing Pete Sampras's record of seven Wimbledon titles, won the last of his 16 majors at the 2010 Australian Open.

Fourth seed Andy Murray tackles flamboyant French shot-maker Richard Gasquet who was two sets to love ahead of the Scotsman in their fourth round meeting here in 2008 before the Scot rallied to win.

The other last 16 ties see America's final representative Mardy Fish meet last year's runner-up Tomas Berdych while Polish qualifier Lukasz Kubot faces Feliciano Lopez who put out three-time runner-up Andy Roddick.

Spain's David Ferrer takes on Frenchman Jo-Wilfried Tsonga while Australian qualifier Bernard Tomic, the first 18-year-old to make the fourth round in 21 years, goes up against former semi-finalist Xavier Malisse of Belgium.

In the women's last 16, Serena and Venus Williams, with nine titles between them, are still on course for a fifth all-sister final.

Both have made light of their lengthy lay-offs to make the last 16 where Serena faces France's Marion Bartoli, the 2007 runner-up, while Venus takes on Tsvetana Pironkova who knocked her out in the quarter-finals last year.

Serena looked impressive in defeating Russia's Maria Kirilenko 6-3, 6-2 on Saturday, where she fired 10 aces and 32 winners.

Top seed Caroline Wozniacki will aim to make the quarter-finals for the first time when she faces gritty Slovak Dominika Cibulkova.

But most eyes will be on 2004 champion Maria Sharapova who faces China's Peng Shuai.

The other last 16 ties see big-hitting Sabine Lisicki, the conqueror of French Open winner Li Na, face Petra Cetkovska of the Czech Republic while Austria's Tamira Paszek takes on Russia's Ksenia Pervak.

Nadia Petrova of Russia meets fourth seeded Belarusian Victoria Azarenka while 2010 semi-finalist Petra Kvitova faces Yanina Wickmayer.