Victoria Azarenka continued her bid for a fourth Miami Open title with victory over Yulia Putintseva to set up a semi-final encounter with Elena Rybakina.
The Belarusian 27th seed, who won her last title at Miami Gardens in 2016, needed almost three hours to claim a 7-6 (7-4) 1-6 6-3 win against Putintseva.
There was a 45-minute stoppage in the opening set due to a power outage.
Meanwhile, world number four Rybakina beat Greek eighth seed Maria Sakkari 7-5 6-7 (4-7) 6-4.
Rybakina, who is the highest ranked women's player remaining in the tournament, lost in last year's final to the Czech Republic's Petra Kvitova.