Venus Williams was on the verge of being swept out of the BNP Paribas Open.
Then she fought off three match points in the second set and recovered to post a stunning 1-6, 7-6 (5), 6-1 victory over Jelena Jankovic on Saturday to advance to the third round at Indian Wells, Calif.
The 12th-seeded Williams looked down and out after losing 10 of the first 12 games against the Serbian. But she said she knew the match wasn't decided.
"It ain't over til' it's over, and I didn't see no fat lady singing!" Williams said with a laugh in her on-court interview.
The 36-year-old American played through heavy bandaging on her left hamstring. Her right elbow also was ailing.
She dropped 16 of her first 18 service points while digging the big deficit. Then when Jankovic was about to put the match away, Williams scored on a backhand volley and watched Jankovic twice hit long returns.
Jankovic was visibly frustrated after the second set collapse and Williams sailed through the final set to land the improbable victory.
Williams will face Lucie Safarova of the Czech Republic in the third round. Williams knocked off 20th-ranked American CoCo Vandeweghe 4-6, 6-4, 6-1.
Venus is the only Williams sister playing at Indian Wells as top-ranked Serena is sidelined with a knee injury.
"Of course it was not so easy to play against her, and we know each other very long," Kerber said. "We have both up-and-downs in our careers. I was trying today just focusing more on my side of the tennis court, just being focused on my game, because I think the last three years I lose here in the first round."
Denmark's Caroline Wozniacki cruised to a 6-3, 6-0 win over Poland's Magda Linette. The 13th-seeded Wozniacki next faces Katerina Siniakova of the Czech Republic, who posted a 6-3, 7-5 win over 23rd-seed Carla Suarez Navarro of Spain.
"I was happy with the effort. It's always tough playing the first round here," Wozniacki said. "The balls fly, the ball goes fast through the air and slows down once it hits the court and the bounce is very high."
Ninth-seeded American Madison Keys is back from offseason wrist surgery and she rolled to a 6-1, 7-5 victory over Mariana Duque-Marino of Colombia.
Keys will face Japanese teenager Naomi Osaka in the third round. Osaka was a 6-4, 6-2 win over China's Zhang Shuai.
Other top-seeded players to advance were fourth-seeded Simona Halep of Romania and sixth-seeded Agnieszka Radwanska of Poland.
Halep was a 6-4, 6-1 winner over Donna Vekic of Croatia, while Radwanska defeated Spain's Sara Sorribes Tormo 6-3, 6-4.