Ashleigh Barty finished the season in style by beating defending champion Elina Svitolina 6-4 6-3 to add the WTA Finals title to her end-of-season world number one ranking on Sunday. Barty, who became the first Australian to top the WTA rankings at the end of the year since they were introduced in 1975, capped a stellar season in Shenzhen having also won the French Open at Roland Garros in June. Barty became the first Australian to win the WTA Finals since Evonne Goolagong Cawley claimed her second title in 1976. "It's been the most incredible year for me," said Barty, who pocketed a record ВЈ3.4million for her victory in Shenzhen, where the tournament was being held for the first time as part of a 10-year residency. "It's been an incredible new era in women's tennis and to play in front of this spectacular crowd has been amazing." There was little between the pair until the penultimate game of the first set when Barty fended off a break point before putting Svitolina's serve under pressure in the following game. The Australian took the opener when she converted a break point at the third time of asking, punishing Svitolina's second serve with a firm forehand. The tension increased in the second set as neither player was able to hold serve consistently. Svitolina broke early to give herself a lifeline, only for Barty to win the next three games – including two breaks of serve. Yet another slip-up on her own serve allowed Svitolina back into the set. Barty broke yet again, however, claiming the eighth game of the set when she converted her third break point as Svitolina pulled a shot wide and secured her fourth title of the season with a hold to love in the next game. Hungary's Timea Babos won the doubles title for the third year in a row, partnering with Kristina Mladenovic from France to see off Barbora Strycova and Hsieh Su-wei 6-1 6-3 in the final. "We played some great tennis," said Babos. "There was no-one out there on this tournament who could beat us. That's really amazing. "Of course, to share it with Kiki, to play on the biggest stage with her, to get the title together, it's an incredible story. "I'm just really, really happy to lift that trophy again."