Anett Kontaveit is still unstoppable down the stretch of 2021. The No.8-seeded Estonian defeated No.3 seed Karolina Pliskova of the Czech Republic 6-4, 6-0 at the Akron WTA Finals Guadalajara, her 12th straight win.

Kontaveit became the first player in the Guadalajara field to qualify for the semifinals with her straight-sets victory. She is guaranteed to finish in the top two of the Teotihuacán round-robin group.

Streaks at play: Kontaveit came into this match riding a career-best 11-match winning streak, which included title runs at Moscow and Cluj-Napoca, as well as a victory in her first round-robin match this week over reigning Roland Garros champion Barbora Krejcikova. 

However, Pliskova came in with a 3-0 head-to-head record against Kontaveit, so something had to yield.

As it has been for much of the tail end of this year, Kontaveit had the last word, beating Pliskova for the first time in four meetings. Kontaveit is now 28-2 across her final eight tournaments of this season, and she owns a tour-leading 38 match-wins on hardcourts this year.

Stat corner: It took Kontaveit only 57 minutes to collect her second win of the week and seal a spot in the semifinals, in her WTA Finals debut. Kontaveit won 24 of her 29 first-service points (83 percent) and fired six aces to storm to victory.

Pliskova, who is making her fifth straight appearance at the WTA Finals, was unable to convert any of her three break points (which all came in a single game). The Czech leads the tour in aces this season, but she had only four in this match and won just 63 percent of her first-service points.

Words from the winner: "Of course, very thrilled to be in the semifinals," Kontaveit said in her post-match press conference. "I thought I played a very good match. I think it was very important for me to be as consistent as possible. Took some time to get used to her serves. I felt like my game was getting better and better as the match went on.

"I think I wasn't thinking about the fact that I was 3-0 down in previous matches [against Pliskova]. I think every time you step on the court, you have a new opportunity. The previous matches don't really matter. It's a new day and you have to beat the player you're playing against. That's how I approach the match.

"I think it's just really trusting my shots a little bit more, just going for it, but going for it with margins. I think that's been very important, not to go for too much, but still stay aggressive and be in charge whenever possible. When it's not possible, just stay in the rallies, be as consistent as possible."

Key moments: Kontaveit was the first player in danger on serve, as she faced three break points at 1-1. However, the Estonian continued to play her best tennis with her back against the wall, powering her way out of trouble to stay on serve.

With that peril behind her, Kontaveit zipped through her next few service games to lead 5-4. She then used blistering backhands to garner her first break point of the day, which doubled as set point. There, Kontaveit prevailed in a stirring rally, ending it with a putaway in the forecourt to claim the one-set lead.

Kontaveit had been 40-2 in matches this year when she won the first set, and that pattern persisted with ease in Guadalajara as she dominated the second set. She struck an ace to grab the opening game of the set, and she followed with a break in the next game via a forehand winner.

All told, Kontaveit ran away with the last eight games to collect a dominant victory and book her spot in the semifinals of the year-ending championships.