Li Na needed 11 match points to put away Aleksandra Wozniak on Tuesday and book an Indian Wells clash with Dominika Cibulkova, the woman she beat in the Australian Open final.
China's Li, the world number two and top seed in the $12 million combined ATP and WTA tournament, defeated Canada's Wozniak 6-1, 6-4 to secure her quarter-final berth.
She steamed through the opening set in 32 minutes, but needed another hour to finally wrap up the second set against a player whose ranking has tumbled to 241st as she was sidelined by injury.
All 11 of Li's match points came in the final game, with two break points for Wozniak mixed in.
"Welcome to the crazy women's tennis tour," Li said.
"The funny thing is, beginning of the game I was feeling tight, nervous, and then I was feeling like what's going on? Why can't I finish the match?
"But she never gave up, she tried to defend every point. Yeah, it was a little bit tedious in the last game."
Four of Li's nine double faults came in the final game, and she lost her cool briefly when a successful challenge of a line call brought not a point awarded -- on her third match point -- but a replay of the point.
"I was really angry, because I saw I won the point," she said. "But suddenly I heard 'Replay'.
"I was like, 'Replay? What are you talking about?'"
- 'I can still smile' -
Li lost the replayed point and the game went to the first of 10 deuces.
"At least I'm still in the tournament," Li said. "I still can smile."
Cibulkova defeated eighth-seeded Petra Kvitova 6-3, 6-2, and Li said she wouldn't be taking anything for granted against the Slovak.
"Last win (against her) doesn't mean anything because I see she played well here. For me it's always a tough match to play against her."
Jelena Jankovic ended her skid against Denmark's Caroline Wozniacki to set up a quarter-final meeting with second-seeded Agnieszka Radwanska of Poland.
Jankovic, seeded seventh, defeated 10th-seeded Wozniacki 6-3, 6-1 in a battle of former world number ones.
In a rematch of the 2010 final in the California desert won by Jankovic, the seventh-seeded Serbian showed no signs of the back trouble that required several visits from the trainer during her third-round victory over Magdalena Rybarikova on Sunday.
"Yesterday I was a little bit scared," Jankovic said of the pain that began when she wrenched her back on a point early in the match against Rybarikova.
"If I had to play yesterday, I probably wouldn't be able to go on court."
Since her 2010 triumph here, Jankovic had dropped five straight decisions to Wozniacki.
Radwanska advanced with a 7-5, 6-3 victory over France's Alize Cornet.
Italian qualifier Camila Giorgi, who shocked defending champion Maria Sharapova in the third round, couldn't maintain her momentum, falling 6-2, 6-1 to compatriot Flavia Pennetta.
Sixth-seeded Romanian Simona Halep reached the last eight with a 6-2, 1-6, 6-4 victory over rising Canadian star Eugenie Bouchard.
Halep will face Australian qualifier Casey Dellacqua, who advanced on a walkover when American Lauren Davis withdrew with a stomach ailment.