London: Nine Grand Slam champions line-up on Wimbledon`s manic Monday with places in the quarter-finals at stake and most interest centred on the latest chapter in the three-decade long Williams sisters story.
The 26th clash between Serena and Venus, who have won the Wimbledon title five times each, will be the first at the All England Club since the 2009 final.
They will dominate early Centre Court action before the likes of Novak Djokovic, Roger Federer and Andy Murray become the focus of the day.
Serena holds the US, Australian and French Open titles and her record in 2015 reads 35 wins against just one loss.
A sixth Wimbledon title will give her all four majors at once and leave her with just the US Open to conquer to complete the calendar Grand Slam.
Fourth seed Maria Sharapova, the 2004 champion, faces Zarina Diyas of Kazakhstan for a spot in the quarter-finals.
The Russian won Wimbledon in 2004 but since has only made it past the fourth round once since 2006.
Danish fifth seed Caroline Wozniacki faces Spanish 20th seed Garbine Muguruza while sixth seed Lucie Safarova, the French Open runner-up, tackles Coco Vandeweghe, the US world number 47.
Former world number one, Jelena Jankovic, who put out defending champion Petra Kvitova on Saturday, takes on Agnieszka Radwanska, the 2012 runner-up.
Victoria Azarenka, the 2012 and 2013 Australian Open champion, has made the Wimbledon semi-finals twice but the Belarusian 24th seed could face a rough ride against in-form Belinda Bencic.
Bencic`s fellow Swiss Timea Bacsinszky reached her first Grand Slam semi-final at the French Open last month and the 15th seed is favourite to beat world number 48 Monica Niculescu of Romania.
Olga Govortsova is the only qualifier to reach the last 16. The Belarusian faces US 21st seed Madison Keys.
Defending champion 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, faces Spanish 20th seed Roberto Bautista Agut who was voted the most improved player of 2014.
He has lost both of his matches against Federer without winning a set including a fourth round loss to the Swiss at the 2014 US Open.
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.
Karlovic has rained down 136 aces in three matches but trails Murray 5-0 in career meetings.
Fourth seed and French Open champion Stan Wawrinka faces Belgian 16th seed David Goffin who has made the fourth round at Wimbledon for the first time.
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 and the lone American. The world 105 faces a stiff test against US Open champion Marin Cilic.
The other last 16 matches feature Australia`s Nick Kyrgios up against France`s 2007 semi-finalist Richard Gasquet.
Vasek Pospisil, the world number 56, is only the fourth Canadian man to reach the last 16 and he faces Serbia`s 22nd seed Viktor Troicki.
Czech sixth seed Tomas Berdych, the 2010 runner-up, takes on Gilles Simon, the French 12th seed.