Defending champion Petra Kvitova of the Czech Republic defeated Kristina Mladenovic of France 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.