Vesnina in the final will meet Svetlana Kuznetsova, who in her semifinal upset No. 3 seed Karolina Pliskova 7-6 (5), 7-6 (2).
Elena Vesnina denied Venus Williams another great escape, beating the seventime Grand Slam champion 6-2, 4-6, 6-3 Thursday to reach the semi-finals at Indian Wells.
Frenchwoman Mladenovic beat Caroline Wozniacki 3-6 7-6 (7-4) 6-2 to break into the top 20 in the WTA Tour rankings for the first time in her career.
Vesnina jumped out to a 5-0 lead in the first set, but Mladenovic then won three straight games before Vesnina was finally able to close out the set.
A third set that, like the first two, featured multiple service breaks came down to marathon ninth game, in which Kuznetsova saved four break points before Vesnina converted her fifth with a stinging service victor to find herself serving for the match. Williams overcame three match points on her serve on three straight errors by Vesnina in the eighth game that featured six deuces and lasted for 9½ minutes.
This intriguing final will take place at 11 am local time inside Stadium 1, and it would give both players a boost to go into the next Premier Mandatory event in Miami with the BNP Paribas Open title in their cabinet.
"I was in the final nine years ago, so it is nice to be here again". 6-1 3-6 7-6. "She started to put a lot of pressure on me".
Sock had no such problems and he hit the mark right at the start of deciding third set by breaking Nishikori in the opening game as the world number five struggled to find the range on his usually pinpoint groundstrokes.
"I guess I'm on fire", Vesnina said.
Driving winners off both wings, Vesnina raced to big leads in each set, then held off the battling Mladenovic. So I think I would say this was the best match what I have played against her from her side.
For Kuznetsova, it was a third disappointment in as many finals at Indian Wells, this one coming a decade after she fell in back to back finals in 2007 and 2008. Mladenovic later began pushing Vesnina, saving one match point while serving down 5-2. "In those moments, you need to trust your game, and that's what I did well".
Roger Federer and Stan Wawrinka met in an all-Swiss men's final later.