Struggling with her serve and a rash of errors, Serena Williams needed three sets to get by Sloane Stephens 6-7 (3), 6-2, 6-2 and reach the fourth round of the BNP Paribas Open on Tuesday.
Williams committed 52 unforced errors and had nine double faults to go with 13 aces and 31 winners in the up-and-down match played in 90-degree (32 Celsius) heat.
She set up match point with a 128-mph ace and won it when Stephens dumped a backhand into the net, one of her 36 errors.
Williams broke Stephens three times in the final set of her third match at Indian Wells since ending a 14-year personal boycott of the tournament.
Stephens recovered after blowing a 3-1 lead in the first set to dominate the tiebreaker.