Former Wimbledon champion Petra Kvitova and Donna Vekic both won through two matches on Saturday to secure a place in the Berlin Open final.
With Friday’s scheduled quarter-finals having been washed out by rain, Kvitova first saw off No 3 seed Caroline Garcia 6-4 7-6 (7-3) to progress to the last four.
Czech player Kvitova, who won Wimbledon in 2011 and 2014, then returned later to defeat ‘s-Hertogenbosch champion Ekaterina Alexandra 6-3 6-4.
Vekic, meanwhile, knocked out lucky loser Elina Avanesyan 6-2 7-6 (7-0) and then battled past sixth seed Maria Sakkari 6-4 7-6 (10-8) to reach her 12th career final.
Alexandrova was the only semi-finalist not to have played twice on Saturday after Veronika Kudermetova had earlier withdrawn from their last-eight match because of a hip injury.
Second-ranked Jelena Ostapenko fought back from a set down to beat the fourth-seed Anastasia Potapova 5-7 6-2 6-4, in two hours and nine minutes to reach Birmingham Open final on Saturday.
“It’s important to win these kind of matches when you’re sometimes not playing your best, and you just fight for every point,” Ostapenko said.
Ostapenko will face Czech Barbora Krejcikova in Sunday’s final.
In a match-up of the former French Open champions, Ostapenko leads the head-to-head against Krejcikova 4-2, including winning their most recent match last month at the Italian Open but they have never met on grass.
In other news, British No 1 Katie Boulter has been drawn against Krejcikova in the opening round of the Rothesay International in Eastbourne.
Meanwhile, Harriet Dart will play China’s Zhang Shuai – the world No 36 – in the first round.