Williams sisters hog limelight

Serena and Venus Williams will clash at Wimbledon for the first time in six years on Monday, but the sisters' ferocious appetite for success suggests it might be premature to bill it as an emotional final fling.

The sisters, who meet in the most anticipated fourth round tie of the tournament, have reigned supreme for much of the last two decades at Wimbledon, lifting the aptly named Venus Rosewater Dish five times each.

With 27 Grand Slam titles between them, the siblings are well established as two of the greatest female players in the tennis history.

However, 17 years after their first tour-level meeting at the Australian Open, the sisters are still as relentlessly competitive as they were when Richard first put a racket in their hands.

After a troubled period three years ago, when a serious foot injury and her lust for the celebrity lifestyle seemed to have taken its toll, Serena has been reinvigorated by coach Patrick Mouratoglou -- winning seven of the last 11 Grand Slams.

A sixth Wimbledon title this year would mean Serena holds all four major titles at the same time and would put her on the brink of becoming the first woman since Steffi Graf in 1988 to win a calendar Grand Slam.

Novak Djokovic, Roger Federer, Stan Wawrinka and Andy Murray remain on course for the Wimbledon semi-finals ahead of 'manic Monday' when the last-16 takes place.

Six of the top 10 seeds are safely into the business end of the tournament after a first week which saw seventh seed Milos Raonic and 10th-seeded Rafael Nadal defeated on court.

Fifth seed Kei Nishikori withdrew before the second round with a calf injury while eighth-seeded David Ferrer pulled out before the first round.

Defending Djokovic will face South African 14th seed Kevin Anderson in the fourth round, defending a 4-1 career lead.

Anderson won their first meeting in 2008 but since then it's been the world number one who has been on top winning the next four without dropping a set, including a straight sets win at Wimbledon in the second round four years ago.

Federer, 33, chasing a record eighth Wimbledon and 18th major, has dropped just one set so far, in his third round win over Sam Groth.

The Swiss, playing his 17th successive Wimbledon, faces Spanish 20th seed Roberto Bautista Agut, who is in the fourth round for the first time.

Murray, the 2013 champion tackles 36-year-old Ivo Karlovic, the oldest man to make the fourth round at the All England Club since compatriot Niki Pilic in 1976.

The 23rd seed is also the oldest to reach the last-16 of any of the four Grand Slams since 39-year-old Jimmy Connors at the 1991 US Open.

Fourth seed and French Open champion Wawrinka faces Belgian 16th seed David Goffin who has made the fourth round at Wimbledon for the first time, equalling his previous best at a major when he came out of qualifying to reach the French Open last 16 in 2012.

Wawrinka has a 2-0 lead over Goffin with both wins coming on the hard courts of Chennai in 2011 and 2015.

American wildcard Denis Kudla is the lowest ranked player left in the tournament.

The world number 105 was winning a second-tier Challenger tournament at Ilkley in Yorkshire, northern England on the eve of Wimbledon.