Wimbledon 2013: Novak Djokovic, Serena Williams in spotlight after stars slump

Novak Djokovic and Serena Williams will be under intense pressure at Wimbledon on Thursday as the All England Club comes to terms with one of the most astonishing days in the history of the tournament. (I'm not finished yet, says Roger Federer)

The famous old courts of the grass-court Grand Slam were rocked like never before on Wednesday as seven former world number ones crashed out, with defending champion Roger Federer and world number three Maria Sharapova the biggest names to fall. (Unscathed Murray into third round)

With the established order under threat, Djokovic, the world number one and reigning Australian Open champion, will be desperate to avoid a giant-killing when he faces American Bobby Reynolds, ranked 156th, on Centre Court.

Williams, the women's world number one and defending champion, will be in the same position against France qualifier Caroline Garcia on Court One.

Other big guns hoping to avoid embarrassing exits include Spanish fourth seed David Ferrer, who plays compatriot Roberto Bautista Agut, and former US Open champion Juan Martin del Potro, who opens the Centre Court programme against Canada's Jesse Levine.

Polish fourth seed Agnieszka Radwanska, beaten by Serena in last year's final here, takes on Mathilde Johansson in the other Centre Court clash.

Federer's run of 36 consecutive appearances at the Grand Slams came to an end in stunning fashion as the seven-time Wimbledon champion was beaten by Ukrainian journeyman Sergiy Stakhovsky -- his earliest exit in south-west London since a first round defeat to Mario Ancic in 2002.

"I won't panic. I will go back to work. This wasn't supposed to happen but I will be back next year," Federer said when asked if the defeat marked the end of his dominance at Wimbledon.

The Swiss great, who has now won a title only once in his latest 14 Grand Slam appearances, wasn't the only high-profile casualty on a day which brought the condition of the slippery courts under close scrutiny.

Sharapova, a former Wimbledon champion, slumped to a shocking 6-3, 6-4 loss against Portuguese qualifier Michelle Larcher De Brito and then hinted the grass was partially to blame.

"I don't think I've ever fallen three times in a match before in my career, so that was a little strange," she said.

Seven players, five men and two women, were forced to either retire during matches or pull out beforehand as a result of injuries.

It was a record for one day at a Grand Slam and started with 18th seed John Isner's exit after just two games against Adrian Mannarino.

World number two and Australian Open champion Victoria Azarenka withdrew just minutes before she was due on Centre Court to face Italian veteran Flavia Pennetta for a place in the third round with a knee injury.

"The court was not in a very good condition My opponent fell twice; I fell badly; there were some other people who fell after," Azarenka said.

Steve Darcis, the first round conqueror of Rafael Nadal, withdrew with a shoulder injury.

French sixth seed Jo-Wilfried Tsonga and Croatian 10th seed Marin Cilic also pulled out, while former world number one Caroline Wozniacki limped through a straight sets defeat against Petra Cetkovska after suffering an ankle injury.