Switzerland's Belinda Bencic will play Anastasia Pavlyuchenkova in Sunday's Kremlin Cup final in Moscow after beating Kristina Mladenovic 6-3 6-4.
Third seed Bencic came through a high-quality encounter against her French opponent in one hour and 35 minutes, and in doing so secured her place in the season-ending WTA Finals in Shenzen.
The 22-year-old sealed the eighth and last WTA Finals singles place by reaching the final in Moscow and out-performing Kiki Bertens, who lost to Mladenovic in the quarter-finals.
"I'm so happy I reached the top eight. It was a huge goal for me this season and so last-minute," Bencic said on court in her post-match interview.
"I was so nervous before the match, but also reaching the final here (in Moscow) is amazing. I'm so happy."
Russian Pavlyuchenkova squandered a match point in a second set tie-break, but came through 6-4 6-7 (6) 6-1 against the Czech Republic's Karolina Muchova, who reached the last eight at Wimbledon last summer.
At the Luxembourg Open, German second seed Julia Georges overcame third seed Elena Rybakina, from Kazakhstan, 6-3 6-4 to set up a final showdown on Sunday against Jelena Ostapenko.
Latvian Ostapenko fought back to beat Russian sixth seed Anna Blinkova 3-6 6-3 6-2.