Naomi Osaka's withdrawal preceded a fine birthday present for Johanna Konta, while there were three-set quarter-final wins for Karolina Pliskova and Maria Sakkari at the Internazionali d'Italia.
Top seed Osaka was forced to pull out in Rome ahead of her last-eight clash with Kiki Bertens due to a hand injury, opening up the draw for the remaining players.
Konta celebrated turning 28 in style by winning a three-setter with Marketa Vondrousova, while Pliskova also lasted the distance against Victoria Azarenka to seal a landmark win.
And Sakkari roared back against Kristina Mladenovic to maintain her hopes of triumphing at the WTA Premier event.
HAPPY BIRTH-CLAY, JO…
Konta is enjoying a career resurgence. The Briton reached a first final in almost 12 months in Rabat a fortnight ago, while she is now in her biggest semi since Wimbledon in 2017.
It was a back-and-forth match against Vondrousova, but ultimately Konta ran out a 6-3 3-6 6-1 victor.
Before this year, Konta had never managed to win three main-draw matches on clay in a given season but she now faces Bertens for a place in the final.
500 NOT OUT FOR PLISKOVA
In a battle between two former world number ones, Pliskova ousted Azarenka 6-7 (5-7) 6-2 6-2 for her 500th career victory.
Pliskova, this season's leader in three-set wins, was beaten by the same opponent in Stuttgart last month but has now levelled their head-to-head meetings at 4-4.
"I think the last couple years I know I'm playing a lot of three-setters," said Pliskova.
"I'm not panicking if I lose first set or even the second. I'm just there. I keep fighting. I feel quite confident coming to the third set, because I know I won quite a lot in last couple of years."
Mladenovic seemed destined for the semis after taking the first set against Sakkari, but the Greek roared back to triumph 5-7 6-3 6-0.