MADRID -- Defending champion Petra Kvitova defeated Kristina Mladenovic 6-3, 7-6 (5) to reach the third round of the Madrid Open on Monday.
The second-seeded Kvitova outlasted Mladenovic by winning the last three points in the tiebreaker to close out the match in nearly two hours.
"I'm glad I won the tiebreak. That is my kind of issue sometimes, but overall it was pretty tight," said Kvitova, who is seeking her fourth Madrid Open title. "I fought hard in the end."
She was in control until losing her serve midway through the second set, letting the French qualifier back into the match.
"Those two games when I was down 5-4 and 6-5 was very intense on my serve and I'm glad I didn't give her the chance, which was my strength, I think," Kvitova said.
Kvitova had seven aces at the "Magic Box" center court en route to her eighth straight win in Madrid. She is the most successful women's player in the tournament with 28 wins and six losses. Her other titles in the Spanish capital came in 2011 and 2015.
Mladenovic was the runner-up in Madrid in 2017.
Kvitova will next face wild card Sorana Cirstea or former No. 4 Caroline Garcia.
In other second round matches, seventh-seeded Kiki Bertens defeated Jelena Ostapenko 6-4, 6-3 to stay on track to make it to her second straight final in Madrid, while eighth-seeded Sloane Stephens got past Victoria Azarenka 6-4, 2-6, 6-2. Ashleigh Barty needed three sets to beat Danielle Collins.
On the men's side, Marin Cilic beat Martin Klizan 6-4, 2-6, 7-6 (0), while Karen Khachanov edged Jaume Munar 6-4, 6-7 (5), 6-3. Gael Monfils defeated Andreas Seppi 6-3, 6-1, and Richard Gasquet ousted Alejandro Davidovich Fokina to set up a second-round matchup against Roger Federer, who is making his return to clay-court tournaments after two seasons.
Three Americans advanced to the second round: Frances Tiafoe beat Nikoloz Basilashvili in three sets, Taylor Fritz got past Grigor Dimitrov in two tiebreakers, and Reilly Opelka defeated Pablo Carreno Busta 7-6 (5), 6-4. Fritz will face top-seeded Novak Djokovic on Tuesday.