Aryna Sabalenka warded off the challenge of Victoria Mboko 7-6 (7-0) 6-4 to progress to the semi-finals at Indian Wells.
The Belarusian world No 1's mental strength proved decisive in the first set, winning the tie-break to love - a career first.
The second set followed a similar script with Mboko clawing her way back to 5-4 and threatening another tie-break but four-time Grand Slam champion Sabalenka closed it out to reach the semi-finals.
Sabalenka gave her opponent a ringing endorsement: "She is definitely a future Grand Slam champion.
"It's incredible to see how brave these young girls are these days. They go out there and go after their shots. They're aggressive and they fight," Sabalenka said afterwards.
"I'm happy with the win, even though a couple of things weren't really working well today. I still managed to win though. I don't think she broke me."
Sabalenka, 27, will next play Linda Noskova, who ended Australian qualifier Talia Gibson's fairytale run 6-2 4-6 6-2, the Czech reaching her second WTA 1000 semi-final and her first at Indian Wells.
Elina Svitolina secured a stunning 6-2 4-6 6-4 victory over world No 2 Iga Swiatek.
Swiatek struggled early against Svitolina, with the Ukrainian capitalising on five double faults to secure three breaks and take the opening set in 38 minutes.
Swiatek found her rhythm in the second to force a decider, but Svitolina regained the upper hand by securing the only break in a closely fought third set before confidently serving out the match.
"I'm extremely happy, it was a tough match," said Svitolina, who is back in the semis for the first time in seven years.
"Iga always brings a bit extra out of me with that fighting spirit. I had to really push myself to close that match."
Australian Open champion Elena Rybakina advanced with a 6-1 7-6 (7-4) win over Jessica Pegula to reach another Indian Wells semi-final where she will play Svitolina.
Jannik Sinner cruised into the semi-finals of the BNP Paribas Masters at Indian Wells with a 6-1 6-2 victory over Learner Tien.
Sinner was only on court for 67 minutes on Thursday during a dominant display against 25th seed Tien.
This comprehensive victory keeps four-time Grand Slam champion Sinner on course as he strives for a maiden title in 2026.
Up next for him is Alexander Zverev, who won in equally emphatic fashion against Arthur Fils by a 6-2 6-3 score to set up their semi-final.
Zverev said it was a special feeling to complete his set of ATP Masters 1000 semi-finals at Indian Wells and join an elite group comprising former world number ones Novak Djokovic, Rafa Nadal, Roger Federer and Andy Murray.
"It's very special to be one of five players in history to ever do it. It's something that I'm very proud of. It's a great thing to have in your career," Zverev told reporters.
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