GUADALAJARA, Mexico - No.1 seeds Barbora Krejcikova and Katerina Siniakova advanced to the final of the Akron WTA Finals Guadalajara after defeating No.4 seeds Nicole Melichar-Martinez and Demi Schuurs 3-6, 6-3, [10-5] in Tuesday's semifinal. The Czech duo will face No.3 seeds Hsieh Su-Wei and Elise Mertens, who beat No.2 seeds Shuko Aoyama and Ena Shibahara 6-2, 6-2, for the title on Wednesday. 

Wednesday's final will feature the reigning Roland Garros champions and Wimbledon champions, and there is more than just the WTA Finals Martina Navratilova Trophy on the line. The winner will decide the Year-End No.1 between current No.1 Hsieh and No.2 Siniakova. The two teams faced off in group play for the first time, with the Czechs dominating in a 6-3, 6-1 win earlier this week. 

Playing in their third WTA Finals and second as the top seeds, Krecjikova and Siniakova are bidding to cap off a phenomenal season that saw them capture Olympic gold, Madrid, and their third major title at Roland Garros. The Czechs are looking to go one better than their first foray at the WTA Finals in 2018 where they finished as runner-up to Timea Babos and Kristina Mladenovic. Tuesday's victory also kept alive Siniakova's chase to end the season as the Doubles No.1.

Playing in their first WTA Finals as a team, Melichar-Martinez and Schuurs came through the El Tajín group with a 2-1 record, recording wins over No.5 seeds Stosur/Zhang and No.7 seeds Jurak/Klepac. 

In the first ever meeting between the two teams, Melichar-Martinez/Schuurs were the clutch team in the opening set, coming through on the big points. The American-Dutch team pulled away in the opening set by going 3 for 3 on deciding points, breaking the Czechs on their only break point chance of the set.

"I think we needed to improve our overall game, we needed to be more aggressive," Siniakova said. "I think it worked. We made a lot of mistakes at the beginning but we kept fighting."

Krejcikova/Siniakova righted the ship in the second set. After landing just 43% of their first serves in the first set, the Czech duo served at 71% in the second. Break points may have been at a premium in the opener, but the teams combined for 10 break points in the second set. Krejcikova/Siniakova earned their first break immediately in the second set and raced out to a 3-0 lead. 

Melichar-Martinez/Schuurs did well to get the break back at 3-4 but the Czechs were undeterred. They broke and served out the st at love to force a match tiebreak. Riding the wave of their comeback, Krejcikova/Siniakova broke open the tiebreak with a 5-1 lead and closed out the win after 1 hour and 29 minutes. 

"I have to say big credit to Niki and Demi, they've been playing well during the whole season and today the match was really difficult, really tough," Krejcikova said. "I'm really happy we got through but I would like to congratulate them on an amazing season." 

Krejcikova/Siniakova are the only team at this year's WTA Finals to maintain an undefeated record through group play. Krejcikova beamed at the thought of getting her hands on the WTA Finals Martina Navratilova Trophy on Wednesday.

"We all love Martina back home and we really appreciate what she did for tennis and what a big player she is," Krejcikova said. "I'm so happy we have the same language and we can talk together. She gives us really good tips. Let's believe tomorrow will be our day and we'll get the trophy."

The second semifinal saw Hsieh and Mertens post their most convincing win of the week so far. They needed only 67 minutes to dismiss Aoyama and Shibahara for the third time this season, having also defeated the Japanese duo 6-4, 1-6, 6-3 in the Wimbledon semifinals and 6-2, 6-0 in the Indian Wells semifinals.

Hsieh and Mertens were particularly sharp in backing up each other's deliveries with finishing volleys, with their sole brief lapse coming at the start of the second set when Mertens dropped serve. On return, they were equally adept at targeting the Aoyama serve, capturing it three times in total.

Aoyama's supreme scampering led to a scattering of highlights for her team, but not enough to dent the Hsieh/Mertens momentum as the Chinese Taipei-Belgian pair raced into their first title match at the WTA Finals together.

It will be Hsieh's fourth appearance in the final, having previously been champion in 2013 with Peng Shuai, and runner-up in 2014 (with Peng) and 2019 (with Barbora Strycova). However, Mertens will be playing for the WTA Finals title for the first time.