Madison Keys beat Venus Williams to reach her first Grand Slam semi-final and end the possibility of an all-Williams contest at the Australian Open in Melbourne.
The unseeded 19-year-old came through 6-3 4-6 6-4 in one hour and 54 minutes.
The American goes on to face top seed Serena Williams, who swept past 11th seed Dominika Cibulkova 6-2 6-2.
Keys overcame a recurrence of the upper leg injury that hampered her at Wimbledon last year, requiring a medical timeout off court during the second set.
“It was definitely kind of a flashback to Wimbledon for me,” she said. “I have had some problems with that part of my leg, so it was kind of an overwhelming moment.
“It was kind of scary but luckily I was able to catch it before I did any real damage to it.”
Serena Williams fired down 15 aces in a comprehensive 65-minute win over last year’s finalist Cibulkova.
The 33-year-old American has won the title on all five occasions she has made it past the quarter-finals.