Top-seeded Caroline Wozniacki reached the Tournament of Champions final after beating Bulgaria's Tsvetana Pironkova 6-4, 6-1 on Saturday.
In the final Sunday, Wozniacki will play either Nadia Petrova of Russia or Roberta Vinci of Italy.
Supported by an enthusiastic crowd in Sofia's Arena Armeec Hall, Pironkova matched Wozniacki at the start of the first set but from 4-4 the Dane won seven consecutive games to lead 6-4, 5-0.
"I feel sorry to beat Pironkova in front of her fans at home, but I am happy to reach the final and hope the fans will support me on Sunday," Wozniacki said.
One fan she could count on was No. 1 golfer Rory McIlroy, who was in Sofia to support his girlfriend.
Playing for her third WTA title of the year in her fourth final has ensured Wozniacki will return to the top 10 when the rankings come out on Monday. She will rise one spot to No. 10, swapping with Marion Bartoli.