Serena Williams said she was "heartbroken" by having to retire from her Wimbledon doubles with sister Venus because of a viral illness which saw her close to fainting and in tears.

Serena, the 32-year-old world number one singles player, called the doctor to Court One just after she and Venus had warmed up for their second round match against Kristina Barrois and Stefanie Voegele.

Extra time goals from Kevin de Bruyne and Romelu Lukaku sent Belgium into the World Cup quarter-finals for first time in 28 years with a 2-1 win over the United States on Tuesday.

American keeper Tim Howard had made a string of fine saves to keep Marc Wilmots' men at bay during the 90 minutes in Salvador.

Angel Di Maria scored in the 118th minute Tuesday to give Argentina a 1-0 win over Switzerland after extra time and a spot in the World Cup quarterfinals.

With a penalty shootout looming, Lionel Messi made a surging run toward the Swiss area and laid the ball off to Di Maria on the right, and the winger sent a left-foot shot past diving goalkeeper Diego Benaglio.

Australia's world number 144 Nick Kyrgios caused one of the greatest Wimbledon sensations on Tuesday when he sent world number one and 14-time Grand Slam title winner Rafael Nadal crashing to a shock fourth round defeat.

The 19-year-old Kyrgios, making his Wimbledon debut, clinched a fearless 7-6 (7/5), 5-7, 7-6 (7/5), 6-3 victory to become the first wildcard in 10 years to make the quarter-finals at the All England Club.

Nigeria coach Stephen Keshi has confirmed he has quit the Super Eagles in the wake of Monday's World Cup last 16 loss to France.

"Friends, it has been a good run and I have enjoyed every moment. It's been an honor coaching the SuperEagles. It is however time to bow out," he posted on his official twitter page.

Simona Halep booked her first Wimbledon quarterfinal appearance as the Romanian third seed eased to a 6-3, 6-0 victory against Kazakhstan's Zarina Diyas, while former finalist Sabine Lisicki also made the last eight after surviving an injury scare on Tuesday.

Halep had never been beyond the second round in her three visits to the All England Club, but the 22-year-old has been in fine form this year, reaching the French Open final last month, and she demolished world number 72 Diyas in just 57 minutes in a fourth round tie delayed from Monday due to bad weather.

Formula One boss Bernie Ecclestone says the sport may say goodbye to one of its most historic tracks at Monza.

Monza's current deal was agreed to in 2010 and Ecclestone believes it is unlikely to be renewed when it runs out at the end of 2016.

The present French side can avenge the painful defeats of their predecessors in the 1982 and 1986 World Cup semi-finals when they face Germany in Friday's quarter-final, said Maxime Bossis, who played in both of those games.

Bossis, who in between those two losses was an integral part of the French side that won the 1984 European Championship at home, in particular wants revenge for the traumatic defeat in the 1982 finals in Seville.

A Singaporean businessman was found guilty of corruption Tuesday after a judge ruled that he offered three Lebanese referees free services of prostitutes in return for rigging future matches.

Nightclub owner Eric Ding Si Yang, 32, could face up to 15 years in prison and a fine of up to Sg$300,000 ($240,000) for bribing referee Ali Sabbagh, 35 and assistant referees Ali Eid, 34, and Abdallah Taleb, 38.

Liverpool have completed the signing of Adam Lallana after the Southampton and England midfielder successfully underwent a club medical on Tuesday.

The transfer fee agreed by Southampton for the 26-year-old midfielder is believed to be around £25million (31million euros) and he will be on a five-year contract.