Brisbane - Karolina Pliskova said she refused to panic despite falling behind a set and a break to Yulia Putintseva in the opening round of the Brisbane International on Monday.
Pliskova, a former world number one, appeared headed for an early exit when she stumbled against Putintseva late in the first set.
But she recovered from 2-0 down in the second to win 4-6, 6-3, 6-4 in two and a quarter hours at the Pat Rafter Arena.
The 26-year-old Czech said despite surrendering the first set, she never felt in any real trouble against Putintseva.
"Even though I was losing a set and a break in the second, I was still pretty positive, because I felt (even though) I'm missing, it's only small margins here and there," she said.
"I just felt like the ball on the racquet felt pretty good."
Pliskova has a good record in Brisbane, winning in 2017 and reaching the semi-finals in 2018.
"I feel it's pretty fast, which is important for my game," Pliskova said.
"I can hit some aces, which I did today, and if I play aggressive there is a chance that I am going to make a lot of points, so I feel good on this court for sure."
Australian wildcard Kimberly Birrell pulled off a massive upset when she stunned world number 10 Daria Kasatkina in three sets.
Birrell, 20, had only ever won one match on the main WTA tour but showed great composure to come from 3-5 down in the third set to win 5-7, 6-4, 7-6 (7/3) in three hours, six minutes.
"I was just trying to stay positive - I was just telling myself to just keep fighting and keep asking the questions," Birrell said.
She will now play Lesia Tsurenko in the second round after the Ukranian beat Romania's Mihaela Buzarnescu 6-0, 6-2.
Birrell's fellow countrywoman Destanee Aiava also moved into the second round with a 6-3, 7-6 (7/2) upset over Frenchwoman Kristina Mladenovic and will now play reigning US Open champion Naomi Osaka.
Croatia's Donna Vekic was too strong for Magdalena Rybarikova of Slovakia, winning 6-1, 6-2 to set up a second-round clash against sixth-seeded Dutchwoman Kiki Bertens, who downed Belgian Elise Mertens 6-2, 6-7 (6/8), 6-4.
Results from matches played at the ATP/WTA Brisbane International at the Queensland Tennis Centre on Monday (X denotes seed):
Grigor Dimitrov (BUL X6) bt Yoshihito Nishioka (JPN) 6-3, 6-4
Milos Raonic (CAN X5) bt Aljaz Bedene (SLO) 6-0, 6-3
Lesia Tsurenko (UKR) bt Mihaela Buzarnescu (ROU) 6-0, 6-2
Karolina Pliskova (CZE X5) bt Yulia Putintseva (KAZ) 4-6, 6-3, 6-4
Destanee Aiava (AUS) bt Kristina Mladenovic (FRA) 6-3, 7-6 (7/2)
Kimberly Birrell (AUS) bt Daria Kasatkina (RUS X7) 5-7, 6-4, 7-6 (7/3)
Donna Vekic (CRO) bt Magdalena Rybarikova (SVK) 6-1, 6-2
Kiki Bertens (NED X6) bt Elise Mertens (BEL) 6-2, 6-7 (6/8), 6-4