Chinese teenager Zheng Qinwen extended her rise up the rankings Saturday by claiming a spot in her first Hologic WTA Tour singles final at the Toray Pan Pacific Open.

Zheng squeaked past 13th-ranked Veronika Kudermetova 5-7, 6-3, 7-6(3) in a match that took 3 hours and 4 minutes. The victory marks Zheng's fifth win over a Top 20 player in her career, all coming this season.

"After the match when I won the last point, the feeling was incredible," Zheng said. "The opponent, she's playing unbelievable tennis. She has a really good serve and hits the ball hard, she moves well.

"I'm so glad in the tiebreak I choose sometimes the right ball and made a good effort to win the match. It's my first time in the final. I'm so happy."

In Sunday's final, Zheng will meet Liudmila Samsonova, whose surge through the second half of the season continues with a trip to her third singles final of the year.

The World No.30 Samsonova defeated 28th-ranked Zhang Shuai 7-6(4), 6-2 in a hard-hitting semifinal to reach Sunday’s championship match in Tokyo. Samsonova is currently an undefeated 3-0 in WTA singles finals in her career.

This time last year, Zheng was ranked outside of the Top 150, but the 19-year-old has repeatedly proved over the last 12 months that she can contend with the elite players on tour. This week has been no exception, as she ousted No.1 seed Paula Badosa in straight sets in the second round.

Zheng was tested Saturday by Kudermetova, who is in the Top 10 in the Race to this season's WTA Finals. Kudermetova came back from 4-1 down in the first set to take it, after holding break points in each of Zheng's service games.

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However, Zheng leaped to another 4-1 lead in the second set and she held on to that advantage this time around, leveling the match at one set apiece. The pair moved into an intense third set, which was settled by a tiebreak after both players held serve all the way through.

In the decisive tiebreak, a volley winner gave Zheng the first mini-break at 3-2, which she followed up with two commanding service winners to lead 5-2. On Zheng's second match point at 6-3, Kudermetova fired a return long, and Zheng was into her first final.

Zheng is the second teenager to reach a final at WTA 500-level or higher this season, joining Coco Gauff, who reached the Roland Garros final at age 18.

As for Samsonova, she has won 17 of her last 18 matches, including two consecutive titles in Washington, D.C. and Cleveland. Her only loss since July came in the Round of 16 at the US Open, where she saw a 13-match winning streak snapped by Ajla Tomljanovic.

Samsonova fired 40 winners in Saturday's 1-hour and 27-minute semifinal, well outpacing her 25 unforced errors. Thirteen of those winners were aces, which gives her a total of 34 in her four victories this week.

After an early exchange of breaks, Samsonova and Zhang settled into a rhythm of fast-paced groundstrokes as they moved inexorably into a first-set tiebreak.

Samsonova took command with fiery forehands down the stretch of the breaker to reach set point at 6-4, which the powerful server converted with her seventh ace of the set.

Zhang had three game points for a 2-0 lead in the second set, but Samsonova returned to top gear from there, with her high-octane game garnering her an immediate break back. Samsonova cruised through the rest of the affair, winning the final four games of the clash.

"I’m feeling so happy because I’m in another final in [the last] two months," Samsonova said in her post-match press conference. "It’s amazing. I never think it’s going to be possible, something like this, so I’m incredibly happy."

Looking ahead to the final, Zheng leads Samsonova 1-0 in their head-to-head. As a qualifier, Zheng surprised second-seeded Samsonova in the first round of Palermo on clay last year.