WIMBLEDON, England — Five-time champion Venus Williams has been ousted in the quarterfinals at Wimbledon, losing 6-2, 6-3 to 82nd-ranked Tsvetana Pironkova of Bulgaria.

The second-seeded Williams, who had reached the Wimbledon final in eight of the past 10 years, was undone by a slew of unforced errors and double faults on Tuesday in the biggest upset of the women's tournament.

The result rules out another all-sister final between Venus and Serena Williams, the defending champion who faces China's Li Na in a later quarterfinal.

Venus Williams never got untracked against the 22-year-old Pironkova, who was the lowest-ranked player left in the women's draw and had never previously progressed past the second round of a Grand Slam.