Wimbledon: Jelena Jankovic became the latest high-profile casualty at Wimbledon as she lost to Tamarine Tanasugarn.
The second seed was visibly impeded by a knee injury as she collapsed to a 6-3 6-2 defeat on Court 18.
Tanasugarn, who herself needed treatment for a back complaint during the second set, is through to the quarter-finals for the first time.
Awaiting her is defending champion Venus Williams, who reached the last eight with a 6-2 6-4 win over Alisa Kleybanova.
Kleybanova, playing in only her third Grand Slam event, rarely troubled the four-time winner on the so-called graveyard of champions.
She did, however, save four match points and earn a late break of serve as Williams struggled to seal her victory.
Serena Williams is also safely through to the last eight after a 6-3 6-3 win over fellow American Bethanie Mattek.
Serena, twice the Wimbledon champion, will meet either Agnieszka Radwanska for a place in the semi-finals and could yet meet her older sister in Saturday's final.
Radwanska reached the last eight by winning a see-saw match against fourth seed Svetlana Kuznetsova, who she beat in straight sets in the second round of the Australian Open.
The Polish 14th seed won the first set before Kuznetsova dominated the second and then opened a commanding 4-1 lead in the third.
However, Radwanska turned the tide by breaking back in the sixth game and went on to complete her victory at the second attempt.
China's Zheng Jie beat Agnes Szavay to reach her first Wimbledon quarter-final, following up her stunning victory over Ana Ivanovic with a convincing 6-3 6-4 success.
The world number 133, who missed much of last season with an ankle injury, will face Nicole Vaidisova for a place in the semi-finals.
Vaidisova fought back from a set down to beat eighth seed Anna Chakvetadze 4-6 7-6 6-3, crucially winning the second-set tie-break 7-0.
The 18th seed then secured a decisive break at the start of the third set.
Nadia Petrova, the 21st seed, ended the run of Alla Kudryavtseva, who beat Maria Sharapova in the second round.
Petrova proved much too strong for her fellow Russian as she won 6-1 6-4 to move into the last eight, where she will meet fifth seed Elena Dementieva after she thrashed Shahar Peer 6-2 6-1.