SINGAPORE — An unwavering Elina Svitolina claimed the biggest title of her career with a gritty comeback victory against Sloane Stephens at the season-ending WTA Finals in Singapore.

The Ukrainian once again dug deep to triumph 3-6, 6-2, 6-2 in two hours and 23 minutes on Sunday. She is the first player to go through the WTA Finals undefeated since Serena Williams in 2013.

Svitolina has been in brilliant, aggressive form in Singapore, beating defending champion Caroline Wozniacki, Czech players Petra Kvitova and Karolina Pliskova at the group stage, and Kiki Bertens in the semi-finals.

Having started slowly in the semi-finals, it was Stephens who made the running early and she broke Svitolina to love in the second game.

It was a matchup of similar styles between the athletic counterpunchers and lengthy rallies punctuated the contest.

Svitolina looked sluggish after playing the two longest matches in the tournament against Wozniacki and Bertens in the semi-finals.

She saved three break points in the sixth game but was unable to convert two chances of her own in Stephens’ next service game.

Stephens’ blistering forehand dictated, as she ran away with the first set.

A more aggressive Svitolina went for her shots and clawed back into the contest. Even though she still struggled on serve, Svitolina attacked on return and broke twice to wear down a suddenly passive Stephens.

Svitolina fittingly forced a decider in a tournament which has had a record-setting amount of three-set matches.

The 24-year-old’s momentum continued as she produced an astounding run down winner to break Stephens in the second game.

But Stephens wouldn’t roll over as she attacked Svitolina’s serve and broke in the fifth game.

The twists continued as Svitolina hit back immediately and stormed home as a wayward backhand from Stephens sparked jubilation from the number six seed.

Svitolina could rise three spots to world number four on the rankings after her triumph and she has now won nine straight finals.

It ended the tournament’s five-year run in Singapore with the season-finale moving to Shenzhen.

Earlier, Timea Babos and Kristina Mladenovic played a masterclass to upset world number one Barbora Krejcikova and Katerina Siniakova in the doubles decider.

The world number three held the edge throughout to triumph 6-4, 7-5 in one hour and 24 minutes at the Singapore Indoor Stadium.

Babos defended her crown, having won last year’s WTA Finals with Andrea Hlavackova.

Babos and Mladenovic qualified for the decider after a pulsating semi-final, defeating Ashleigh Barty and Coco Vendeweghe 10-8 in the super tiebreak set.

"The first tournament of the season, we won a slam (Australian Open) and the last tournament of the season we won... it’s a privilege," Mladenovic said after the match.

The Hungarian-French pairing closed in on championship glory by breaking in the fifth game of the second set but Babos was unable to consolidate.

Babos upped her game in the 11th game to break Siniakova’s serve and then Mladenovic held her nerve to close it out.

Even though they fell short in the final, the Czechs had already secured the world number one ranking. — AFP