Venus Williams beat Yaroslava Shvedova 7-6 (7-5) 6-3 to reach the Wimbledon semifinals.
It is five-time champion Williams' first Wimbledon semifinal since 2009, when she last met younger sister Serena in a grand slam singles title match.
Kazakhstan's world No. 96 Shvedova has now lost all three of her grand slam singles quarterfinals, though she has reached five women's doubles finals.
Former world No. 1 Williams, seeded eighth in southwest London, will next play Australian Open champion Angelique Kerber (pictured).
The German fourth seed won 7-5 7-6 (7-2) against Simona Halep, extending the Romanian world No. 5's wait for a first grand slam title.
Defending champion Serena Williams beat Anastasia Pavlyuchenkova 6-4 6-4 in her quarterfinal.
The 21-time grand slam winner, seeking her seventh Wimbledon crown, prevailed against her Russian opponent in just over 70 minutes.
The American will next play another Russian, Elena Vesnina, who beat 19th seed Dominika Cibulkova 6-2 6-2 to reach her first grand slam semifinal. The Slovakian has only once got past a major quarterfinal, losing the 2014 Australian Open title match.