Agony for Ana as Venus goes through

Defending Wimbledon champion Venus Williams was given an easy passage into the quarter-finals when Ana Ivanovic retired with a groin injury in the second set of their match on Court One.

Williams had raced through the first set 6-1 in half an hour and Ivanovic was battling to hold her serve in the first game of the second set when she called the trainer.

The 13th seed had her left thigh taped up but was clearly hampered and, although she went on to win the game, she retired in tears at the change of ends.

Serena Williams joined her sister quarter-finals and the pair remain on course for what would be their fourth meeting in the final.

Serena won easily, 6-3 6-1 against Slovakian Daniela Hantuchova who was outclassed from midway through the first set, when the second seed raised her level of performance.

Her next opponent will be Victoria Azarenka, the eighth seed from Belarus who knocked out 10th seed Nadia Petrova in three sets. Azarenka prevailed 7-6 (7-5) 2-6 6-3 against the Russian.

Russia's Elena Dementieva secured her place in quarter-finals with an easy win against a compatriot. The 27-year-old fourth seed, who reached the semi-finals last year, beat Elena Vesnina 6-1 6-3 on Court Two.

Unseeded Italian Francesca Schiavone produced a shock victory to extend her impressive run, beating French 26th seed Virginie Razzano 6-2 7-6 (7/1).

Poland's Agnieszka Radwanska also made it through to the last eight thanks to a straight-sets win against American teenager Melanie Oudin on Court 18.