Darija Jurak, 37, and Andreja Klepac, 35, are the oldest team in this year's Akron WTA Finals Guadalajara field - but despite nearly four decades of combined experience, playing the year-end finale will still be brand new territory for both players.

Jurak made her pro debut in 2001, and competed in her first Grand Slam doubles draw as a 19-year-old at the 2004 Australian Open with Mervana Jugic-Salkic. The Croat won her first WTA doubles title at Monterrey 2014 with Megan Moulton-Levy and had six under her belt before this season. However, after 40 Grand Slam main draws, she had yet to pass the third round.

Klepac played her first pro match in 2004 and debuted in a major doubles draw at Roland Garros 2009 alongside Ekaterina Dzehalevich. Over the years, the Slovenian racked up eight WTA doubles titles with seven different partners, and reached six major quarterfinals.

Road to WTA Finals, singles

Road to WTA Finals, doubles

The pair first teamed up on the ITF Pro Circuit in 2006 and reunited at WTA level in 2014 but won just one match in five tournaments. Seven years later, it was a different story. Though Jurak and Klepac only restarted their partnership in April, they have recorded two titles and two runner-up showings, and their 26-13 record was enough to land them in the season-ending finale.

Clay: On the upswing

Jurak had already delivered indications that 2021 could be a career-best year even before joining forces with Klepac again. In her 41st Grand Slam main draw, alongside Nina Stojanovic, she reached her first ever semifinal at the Australian Open - a run that included a stunning second-round upset of top seeds Hsieh Su-Wei and Barbora Strycova. A month later, Jurak partnered Alexa Guarachi to her maiden WTA 1000 title in Dubai.

Jurak and Klepac took some time to hit their stride, winning one match in their first three tournaments, but reached their first final together in Parma, falling to Coco Gauff and Caty McNally. They backed this up with a run to the last eight of Roland Garros - Jurak's second major quarterfinal immediately after her first, and Klepac's seventh overall.

Grass and hard: The titles start flowing

As the tour moved to faster surfaces, Jurak and Klepac came into their own. They dropped just one set en route to the Bad Homburg title - Jurak's eighth title and Klepac's ninth, but a first together. They repeated the feat at WTA 500 level in San Jose, defeating Gabriela Dabrowski and Luisa Stefani in the title match and rode an eight-match winning streak into the Montréal final, where Dabrowski and Stefani took their revenge.

A third-round run at the US Open was followed by another strong showing on US hard courts at the Chicago Fall Tennis Classic, where Jurak and Klepac upset Shuko Aoyama and Ena Shibahara to reach the semifinals.

The autumn also featured a significant milestone for Jurak, who cracked the Top 10 for the first time in November.

"Some things are earned after years of perseverance, training, sacrifice and determination: the formula for success," she wrote on social media. "Set your goals high and reach upward as far as you can."