Errani, the No. 1 seed and defending champion, capped Friday's run of quarterfinals matches with a 6-4, 6-0 win over seventh-seeded Silvia Soler-Espinosa. Errani ran away with the second set, winning about two-thirds of the points overall.
Vinci, the No. 2 seed, was a 6-1, 6-4 winner over fifth-seeded Lourdes Dominguez Lino. Vinci won 69 percent of the points on serve and saved the only break point Dominguez Lino managed.
Should Errani and Vinci win Saturday, the final would send the players from the world's No. 1 doubles team against each other. Errani and Vinci have teamed to win three of the last six Grand Slam women's doubles titles, including this year's Australian Open. However, they aren't playing doubles this week.
For that to happen, Errani will need to defeat fourth-seeded Klara Zakopalova, who beat Dinah Pfizenmaier 7-5, 6-7 (7-4), 6-1 in her quarterfinal. Zakopalova piled up nine breaks in the match.
Vinci faces Estrella Cabeza Candela in her semi. Cabeza Candela advanced with a 7-5, 6-4 decision over Renata Voracova.
Errani is 3-2 all-time versus Zakopalova, including taking their last three meetings. Vinci won the only time she played Cabeza Candela.
Notable deaths of 2014 [PHOTOS]