World number three Karolina Pliskova battled back to beat Olympic champion Monica Puig 1-6, 6-4 6-4, but says she'll have to do better to go further at Indian Wells.
"I don't even think I deserved to win tonight," third-seeded Czech Pliskova said after recovering from a break down in the third set to reach the third round.
Puig, ranked 43rd in the world, had never taken a set off Pliskova in three prior meetings.
But she was on fire from the baseline early, breaking the big-serving Czech four times in the opening set.
Pliskova, winner of titles in Brisbane and Qatar already this season, was in trouble again in the decisive set, down one break at 0-3
But Pliskova won six of the last seven games to advance despite 34 unforced errors to just 19 winners.
"Hopefully I can get something from it and move on and play better next time," said Pliskova, who is aiming to improve on her semi-final run at Indian Wells last year.
In other second-round matches, 17-year-old American Kayla Day shocked Australian Open semi-finalist Mirjana Lucic-Baroni to earn a clash with French Open champion Garbine Muguruza.