There was still time to start the final on Sunday evening but, because of rain earlier in the grass-court tournament, both women would have been forced to play three times in one day, with most of Jankovic’s 6-3 6-4 quarter-final win over Japan’s Misaki Doi having taken place on Sunday.
Jankovic later went on to beat China’s Zheng Jie 6-7(2) 7-5 6-1 in the semi-finals, with the match finishing just before 6.30pm UK time, so even had they started the final it would almost certainly have run into Monday.
"I’m happy I was able to win my two matches today," said Jankovic. "Two difficult matches, five sets, but the most important thing was I was able to win them both.
"As the match went on, I was playing better and better against Zheng, and all of a sudden in the third set, I was like, ‘yeah I can play.’ I feel like the former number one."
American Oudin, meanwhile, completed her 6-4 5-7 7-5 win over Italy’s Irina Falconi to progress into the last four, where she clinched a 6-4 3-6 6-2 victory over eighth seeded Russian Ekaterina Makarova.
Monday will be Oudin's first career WTA Tour final.
"I’m pretty happy about this week," said Oudin, the world number 208 who reached the fourth round at Wimbledon and the quarter-finals at the US Open in 2009.
"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."