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.

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.

Dementieva has made serene progress through the draw this year, not dropping a set yet, and she was in full control against Vesnina.

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.

Radwanska, seeded 11th, broke serve at the end of each set to end the campaign of 17-year-old Oudin, who battled through qualifying to take her place in the main draw and then knocked out sixth seed Jelena Jankovic in the third round.

Williams will play Radwanska in the quarter-finals on Tuesday.