Angelique Kerber says she never stopped believing despite being just two games away from defeat at the BNP Paribas Open in Indian Wells.
The German battled hard to beat Frenchwoman Pauline Parmentier 7-5 3-6 7-5.
She was staring down the barrel, though, trailing 4-1 in the deciding set, before winning six of the next seven games to book her place in the fourth round.
Kerber said: "When you are in a match like this, you are not thinking about pressure.
"I was thinking to play point-by-point and trying to win the match, when I was 4-1 down in the third set, still believe that I can change the match."
Kerber will come up against Elena Vesnina in the next round following the Russian's 6-4 1-6 6-4 win over Timea Babos.
Fourth seed Simona Halep - on the comeback trail from injury - was ousted by France's Kristina Mladenovic 6-3 6-3, Venus Williams eased past Lucie Safarova 6-4 6-2 while Lauren Davis beat Julia Goerges 6-1 6-4.
Sixth seed Agnieszka Radwanska was dumped out by China's Shuai Peng.
Peng, who has recently returned from a back operation, got the better of the Pole 6-4 6-4.
Another player who has gone under the knife recently, Madison Keys, showed no signs of rustiness as she blitzed Naomi Osaka 6-1 6-4 while Caroline Wozniack had too much for Katerina Siniakova in a 6-3 6-1 win.