Venus Williams saved three match points as she roared back for a 1-6, 7-6 (7/5), 6-1 victory over old foe Jelena Jankovic and a place in the third round at Indian Wells.
The seven-time Grand Slam champion, her right arm bandaged and her serve speed down, surrendered the first set in just 20 minutes and was quickly down a break at 3-1 in the second.
"I definitely wasn't able to do everything I wanted to," she said. "Took me some time to kind of get my head around that.
"You have to get disciplined and just try to deal with what's at hand and try to use the tools you have on this particular day," said Williams, who did so with a vengeance.
She broke Jankovic twice to take a 5-4 lead in the second set before the Serb veteran, like Williams a former world number one, broke in the 10th game to pull level at 5-5.
Serving to save the match, Williams was on the ropes in the 12th game but she saved three match points to force the decider.
Once she came through it, she ran away with the third, buoyed by an enthusiastic crowd.
"It ain't over til it's over," she told her ecstatic fans of her determination to stick with it until the end. "And I didn't see no fat lady singing."
Williams next faces Czech Lucie Safarova, a 4-6, 6-4, 6-1 winner over American Coco Vandeweghe.
Safarova denied Vandeweghe a chance to avenge her semi-final loss to Williams at the Australian Open, where Williams fell in the championship match to her sister Serena.
Jankovic, meanwhile, could only regret her missed opportunities, especially her first match point that Williams saved with a volley winner.
"When she was at the net I was supposed to play that cross forehand but I played down the line and right to her and she made a winner," Jankovic said. "I had everything under control and I just let it slip away."