In her 13th main-draw showing at the Miami Open, Petra Kvitova has broken new ground.

Seeded No.15, Kvitova is into the Miami semifinals for the first time in her career after a 6-4, 3-6, 6-3 victory against No.18 seed Ekaterina Alexandrova on Thursday, the last singles quarterfinal of the tournament.

The power-hitting pair was supposed to square off Wednesday night before rain washed out their match. On a relatively drier Thursday, it was Kvitova who prevailed after 2 hours and 12 minutes.

"I have to say it was a tough one, for sure, especially mentally," Kvitova said in her postmatch press conference. "Ekaterina played amazing. I would say she was really striking the ball very clearly, and it was really difficult to face some serves of hers."

Miami breakthrough: The Two-time Wimbledon champion Kvitova was in her fourth Miami quarterfinal, but she had never progressed beyond that round before Thursday.

Kvitova previously fell at this stage of the event to three different players, each of whom reached World No.1: Maria Sharapova in 2014, Ashleigh Barty in 2019 and Iga Swiatek last year. Barty and Swiatek went on to win the Miami Open title those years as well.

Alexandrova gave a solid account for herself, but Kvitova would not be denied this time around, dropping serve only once to grit out a close victory and improve to 2-0 against Alexandrova.

"It means a lot, for sure," Kvitova said. "It's a big tournament. I've never been in the semifinal here, so it's nice, especially when I played the quarterfinals in Indian Wells. So I'm happy that the momentum is there."

This is Kvitova's 20th career WTA 1000 semifinal, in her 99th WTA 1000 appearance. She becomes one of just seven players to notch 20 or more WTA 1000 semifinals since the tier started in 2009 -- and the first left-hander to do so.

Key plays: Sturdy forehands by Czech Kvitova gave her an early break in the first set, and she closed out the one-set lead with an ace on her third set point.

However, Alexandrova leveled up in the second set, firing a series of shots on the lines, and she pulled off one amazing backhand crosscourt service return to break for 4-2. Alexandrova held on from there to tie the match at one set apiece.

In the final set, Kvitova won a key game to hold for 4-3, saving a break point in the process, and she rallied from that point forward. Kvitova cracked a crosscourt forehand to force an error and break for 5-3, then converted her second match point in the following game to notch the win.

Both players equaled their winner count with their unforced error count. Alexandrova had 26 winners to 26 unforced errors, while Kvitova had 19 of each. Ultimately, Kvitova's lone extra break in the final set was the determining factor that got her across the finish line.

"I'm glad that my serve helped me in important moments, especially in the third set," Kvitova said. "The chance for the break came. I took it, and yeah, it was very emotional in the end. I'm very happy that somehow I found a way to win it."

Cirstea awaits: Kvitova’s semifinal opponent will be a familiar foe: Romania’s Sorana Cirstea, who earned her career-best win by ranking on Wednesday when she shocked World No.2 Aryna Sabalenka in the quarterfinals.

Kvitova and Cirstea, both born in 1990, have already met ten times in their lengthy careers, with Kvitova holding a slim 6-4 advantage in their head-to-head.

Introducing Sorana Cirstea

Kvitova won their most recent meeting in Cincinnati last year, but Cirstea has already beaten Kvitova once en route to a WTA 1000 final, in the 2013 Toronto quarterfinals.

Kvitova and Cirstea have had equivalent results so far during this month's Sunshine Double: a quarterfinal result in Indian Wells followed by the semifinals this week in Miami.

"It's nice to be playing somebody who is in as good form as me, so it will be a great matchup, for sure," Kvitova said, looking ahead to Cirstea. "We played a few battles already during our years. We practiced here before the tournament started as well.

"It's kind of nice, I have to say, that somebody [else] over 30 as well is playing so nice. It's nice, it's fun. I'm happy for Sorana, how she's playing, with the run she has. Definitely would be nice to face her again."