Anastasia Pavlyuchenkova reached her first Grand Slam semi-final at the 52nd attempt on Tuesday and will be favoured to make the French Open final when she takes on world number 85 Tamara Zidansek of Slovenia.
Pavlyuchenkova, the world number 32, beat doubles partner Elena Rybakina 6-7 (2/7), 6-2, 9-7 in her first quarter-final appearance at Roland Garros since 2011.
"There are so many emotions to reach a Grand Slam semi-final for the first time," said 29-year-old Pavlyunchenkova who had fallen at the quarter-final stage at the majors on six previous occasions since her 2007 debut.
"I always had the tennis. Mentally I'm probably more solid now. Just trying to play smarter tennis. I'm working harder."
Rybakina dumped out Serena Williams in the previous round and raced into a 4-1 lead in the opener. Pavlyuchenkova broke back in the seventh game before the 6ft (1.84m) Russian-born Kazakh dominated the tiebreak.
The Russian levelled the tie courtesy of breaks in the sixth and eighth games of the second set.
In a tense decider, there were four breaks in the first six games before Rybakina cracked in the 16th game, going down tamely on her sixth double fault.
Earlier, the unheralded Zidansek became the first woman representing Slovenia to advance to the last four at a Grand Slam after beating in-form Spaniard Paula Badosa 7-5, 4-6, 8-6.
"It feels overwhelming. It's hard to take it in this fast," said Zidansek, who had never gone beyond the second round of a Slam before this year's Roland Garros.
Zidansek recovered from 3-0 and a double break down in the first set and saved three break points at 6-6 in the decider against Badosa, the 33rd seed with the most clay court wins (17) on the WTA tour this season.
The Slovene took her second match point to continue her dream run. She is two wins away from emulating Maribor-born Mima Jausovec, who won Roland Garros in 1977 while representing Yugoslavia.
Stefanos Tsitsipas hopes to stay on course for a first Grand Slam final when he meets rival Daniil Medvedev in the night match, the last to be played behind closed doors before the easing of a nationwide curfew.
Greek fifth seed Tsitsipas will try to reach a third successive major semi-final, having lost a thrilling five-setter to Novak Djokovic in Paris last year.
Blocking his path is second seed Medvedev, the Russian who hadn't won a match in four previous visits to the French Open but has looked increasingly assured on clay over the past week.
Medvedev, a runner-up at the 2019 US Open and this year's Australian Open finalist, holds a 6-1 head-to-head advantage over Tsitsipas.
He beat the Greek in straight sets in the last four in Melbourne in their most recent meeting.
"He does serve extremely well, I have to say. He has improved over the years with his serve. This is going to be something that I will have to face," said Tsitsipas, who compared Medvedev's serve to that of John Isner.
"Of course, myself playing well, I feel like I don't have to think against who I'm facing or not, I just have to play my game, let the rest be witnessed."
Medvedev could take over the number one ranking if he reaches the final and Djokovic does not.
He has a career win-loss record of 15-20 on clay, but the return of Roland Garros to its traditional May-June slot and far warmer temperatures have helped the Russian shake off bad memories of past editions.
"Definitely a better feeling than losing the first round, going home on Tuesday like I think two or three times I lost here Sunday. It's not a good feeling. I hope it's going to be better with every year," said Medvedev.
The winner will go on to play Alexander Zverev or newcomer Alejandro Davidovich Fokina for a spot in Sunday's final.
Zverev, seeded sixth, is through to the French Open last eight for the third time in four years. He has won his past 12 sets after recovering from two sets down against qualifier Oscar Otte in the first round.
Spain's Davidovich Fokina, who turned 22 last week, is appearing in his first Grand Slam quarter-final.