Jelena Jankovic completed two victories on Sunday to reach the Aegon Classic final in Birmingham.
The Serbian finished her quarter-final against Japan's Misaki Doi, winning 6-3 6-4, then won her semi-final against China's Zheng Jie, 6-7 (2-7) 7-5 6-1.
In the other semi-final, American Melanie Oudin defeated Russia's Ekaterina Makarova 6-4 3-6 6-2.
The final has been held over until Monday at 11:00 BST because of the bad weather in Edgbaston.
Jankovic, winner at Birmingham in 2007, said: "It's been a really difficult day at the office but a good one. You spend 12 hours at the site just watching the rain out of the window. Even when it stopped, I still saw the rain."
Oudin, who has reached her first WTA tour final, said: "I'm pretty happy about this week. I've been 30 in the world before so it's not like I can't get back there again.
"This week, I'm really showing that, playing top-50 tennis again."
Discussing the challenge of facing former world number one Jankovic, the 20-year-old American said: "It's definitely good I've played her before. But she's a great player, she has been in the top 10 for a long time.
"I know recently she hasn't been doing that well but she's a former number one. She knows how to play good tennis."
Tickets valid for Monday, 11 June, Friday, 15 June or Saturday, 16 June - days that were severely affected by the weather - will gain free entry to the final.