SHENZHEN, China - No.1 seed Ashleigh Barty capped off her spectacular season with a fourth trophy of the year, delivering a dazzling performance to dethrone defending champion and No.8 seed Elina Svitolina 6-4, 6-3 in the final of the Shiseido WTA Finals Shenzhen over one hour and 27 minutes.

"Bizarre, if I'm being completely honest," she laughed afterwards when asked to describe the feeling. "It feels like it's been a year that just hasn't stopped. It's been a year of incredible ups and downs - I think more ups than downs. To cap it off with a very, very special night tonight in Shenzhen is really cool."

Expanding on what made her victory so sweet, Barty continued: "To come through a week like this, you have to beat the best of the best. It takes me back to some memories in Miami where I felt like I did that for the first time, beating back-to-back Top 10 players, having that really consistent week. I've grown and developed so much since that fortnight in Miami. To be able to bounce back after the disappointment after my match with Kiki [Bertens] was really important."

Barty, who guaranteed herself the WTA Year-End World No.1 Singles Ranking presented by Dubai Duty Free earlier this week, becomes the second Australian to capture the WTA Finals crown following 1974 and 1976 champion Evonne Goolagong Cawley, and the fifth player to win the tournament as a debutante. The 23-year-old's first victory over Svitolina in six meetings also snaps her opponent's nine-final winning streak stretching back to Zhuhai 2016, and means that she ties Karolina Pliskova with a Tour-leading four titles in 2019. Barty's winning check of $4.42 million is also the biggest ever inmen's or women's  professional tennis.

Having never beaten the Ukrainian before - including suffering a heartbreaking marathon defeat in the fourth round of Indian Wells one that Barty admitted took "a few days" to get over - she ascribed her first success today to "a slight shift in tactics and execution".

Expanding, Barty said: "Tonight it felt like it was a lot more clear, a lot more concise from my end. I took my opportunities when I got them... [The forehand] was a side that I wanted to try to get into tonight. I think it was also important for me to move forward, then to try to bring Elina in a few times as well, which worked really well."

Both players were sharp out of the blocks: though the Shenzhen court has drawn comment this week for its slowness, a series of rapid-fire points as the first eight games passed without so much as a break point demonstrated that accurate placement and strong serving could go a long way to hitting through it.

Only at the business end of the set did opportunities begin to arise - and they would decide the opening act by the finest of margins. Conjuring up a pinpoint lob and backing it up with an emphatic drive volley, Svitolina carved out the first break point of the set - but her forehand drifted just wide on it, and Barty extricated herself from the game with what would be a trademark throughout the match: accurate, line-to-line point construction finished with finesse at net.

A game later, it would be Barty making moves - and although Svitolina bravely fended off two set points, the second with a magnificent pass, a dead net cord garnered the Roland Garros champion a third chance - and this time she rose to the occasion, smacking away a clean forehand return winner.

For the majority of the match, Barty's game would be watertight - particularly on the biggest points. Indeed, she would experience only one loose patch of form, dropping serve for the first time with a handful of errant backhands and a double fault to go down 1-2 in the second set. But the Miami and Birmingham champion responded with her most spellbinding passage of play, reeling off the next three games by excelling in every aspect of the game: weaving a web around the court with her slice, taking on every short forehand and overhead with relish, and demonstrating supreme anticipation on defence.

Desperately clinging on to the match, Svitolina continued to hustle, rushing the net and striking through her backhand to superb effect. The tactic would win her the break back - but Barty would not be denied for long. Winning a series of breathtaking cat-and-mouse points, the Sydney and Beijing runner-up broke again in arguably the finest game of the match - before sealing victory with an emphatic love hold.