A new WTA singles champion is guaranteed at the inaugural ATX Open, with Marta Kostyuk and Varvara Gracheva each reaching their first career final with semifinal victories on Saturday.

In Saturday's afternoon semifinal, No.8 seed Kostyuk of Ukraine swept past No.4 seed Danielle Collins of the United States 6-4, 6-3.

Coming into the event, 20-year-old Kostyuk had reached four previous semifinals at tour level, but had never converted any of those into a final appearance. That all changed with her 84-minute victory over 2022 Australian Open finalist Collins, in their first meeting.

"Obviously a special moment, very emotional," World No.52 Kostyuk said after her win. "I lost four semifinals prior to this match today, and I didn’t know what to expect. Danielle is a great player, a great champion. Very happy that the match turned out this way today."

By the numbers: Another solid week for Kostyuk improves her 2023 win-loss record to 14-6 (including main draws and qualifying). This year, she has also reached quarterfinals at Adelaide International 1 and Hua Hin, as well as the third round of the Australian Open.

Kostyuk had a level ratio between winners and unforced errors, with 17 apiece, while Collins' 13 winners were outpaced by 21 unforced errors. Kostyuk converted four of her seven break points on the day while only losing her serve once.

Key moments: Collins held four break points while ahead 3-2 in the first set, but Kostyuk fended all of those off. In the next game, a powerful Kostyuk return forced a backhand error from Collins on break point, and Kostyuk moved ahead 4-3. That proved to be the only break of the opening set.

In the second set, Kostyuk nearly saw a break lead at 3-2 disappear, but she erased Collins' final break point of the day with an ace before holding for 4-2. In the last game of the match, another forehand winner gave Kostyuk one more break, along with a spot in her first final.

Gracheva outlasts Volynets

In the night session, 22-year-old Gracheva overcame 21-year-old Katie Volynets 6-4, 5-7, 6-4 in a clash between two players who were both seeking their first WTA singles final.

From 4-2 down in the third set, Gracheva reeled off four games in a row to claim the 2-hour and 24-minute win and move into a breakthrough final. Her only previous WTA semifinal came at Chicago in 2021.

"Honestly, [the key was] being more positive with myself, because I went a lot into the emotions," Gracheva said on court, after her win. "Katie, she has a great game, she just doesn’t miss, and to work out the points when you’re a little bit down mentally, it’s just impossible."

World No.88 Gracheva started the event with a huge upset, taking out No.1 seed and 2023 Australian Open semifinalist Magda Linette in the first round. Three of her four wins this week came in three sets.

On Saturday, Gracheva led by a set and a break at 6-4, 2-1 before World No.92 Volynets battled back to level the match at one set apiece. Volynets broke first in the third set to lead 3-2, and she put herself two games away from the win with a rally forehand winner to hold for 4-2.

But Gracheva slammed her own rally forehand winner square on the baseline to get back on serve at 4-4, and she took charge from there, drawing errors from Volynets in the final game to break serve again and make the final.

The pair combined for 17 breaks of serve, with Gracheva garnering one more service break than Volynets to ultimately make the difference.

Looking ahead to Sunday's final, Kostyuk has a slim 3-2 lead in her head-to-head with Gracheva. However, Gracheva won their most recent meeting, which was the 2021 Chicago quarterfinal that put Gracheva into her sole prior WTA semifinal before this week.