SHENZHEN, China - No.1 seed Ashleigh Barty recovered from a set down to overcome No.7 seed Belinda Bencic 5-7, 6-1, 6-2 in one hour and 57 minutes in the second Red Group match of the 2019 Shiseido WTA Finals Shenzhen - wrapping up the year-end world No.1 Singles Ranking presented by Dubai Duty Free in the process, provided she steps on court for one further round-robin match this week.

One of the most intriguing matchups of the week between two WTA Finals debutantes was, before today, one of the most anticipated first-time clashes on the WTA Tour, pitting two of the most tactically savvy players around against each other. Ultimately, it was the Australian who made superior adjustments throughout the match to come through the unknown challenge, striking 30 winners and snapping two Bencic streaks in doing so - the Moscow champion's four-match winning streak, as well as her four consecutive wins against reigning World No.1s.

"It's important to notice what's not working, what is working, adjust the game plan accordingly," said Barty, who has now won from a set down on 11 occasions this year. "I think in particular for tonight, it was important in the first two or three games in the second set to try to reset the tone. I was able to do that with my first service game, first return game, and roll on from there.

"I prefer not to be a set down more often than not. I mean, I want to hang around. I don't want to roll over and give my opponent an easy win."

A cagy opening set saw both players probing each other's games - and focusing on protecting their own serves. Consequently, there would be just two break points across the entire opening act: one saved by Bencic with a service winner in her first service game, and one taken by her in the penultimate game after Barty threw in a pair of double faults and an errant slice serving at 5-5.

Indeed, Bencic slowly getting to grips with the Roland Garros champion's slice had been key to the first set: as it had progressed, Barty had been able to draw fewer errors from the Swiss player with it, and Bencic had instead taken the opportunity to redirect the ball and take control of the rally when faced with the shot. Landing 61% of her first serves compared to Barty's subpar 49%, Bencic also conceded only six points behind her delivery following that first tight hold, and wrapped up the set with her third ace.

"It was obviously a very tight first set without too many opportunities for either of us," recalled Barty. "I think we both served particularly well at times. I think in the end I gave Belinda too many looks at second serves in the first set. That was the key for the second and third sets - try to dominate a little bit more with the first serve and also depth off the ground, which was a massive thing on that court."

Accordingly, those numbers would be reversed in the second set as Barty raised her first serve percentage to 59% while Bencic's fell to 48% - and the momentum, too, would flip. Barty's ability to pivot tactically mid-match has been a defining feature of her success this year - and with Bencic seemingly impervious to her web of slices, the 23-year-old instead took control by surprising her opponent with a driven return winner off that wing to create her first break opportunity of the second set in the second game.

With Bencic eventually conceding her serve for the first time with a double fault, Barty would accelerate through the remainder of the set, running around her backhand to crunch winners with her forehand and racking up five aces - the last to seal her third set point and force a decider.

Over the course of the second set, Bencic's accuracy had deserted her as the 22-year-old tallied 13 unforced errors to only six winners. A medical time-out before the third set got under way temporarily revived her fortunes with a sequence of high-quality points in its opening stages - but again, it was Barty who was able to raise her level even higher.

Pulling off some remarkable volleys to gain the upper hand, the Miami champion was also the recipient of a significant stroke of luck - a dead net cord on break point to capture the Bencic serve for a 2-1 lead. That would also effectively end the resistance of the Dubai champion, who coughed up four cheap unforced errors - contributing to a final total of 30, compared to 17 winners - to fall behind a double break. With Barty now landing 77% of her first serves, that lead was unassailable - and an 11th ace on her second match point sealed victory in style.

Simply taking the court in her second round-robin match will assure Barty of finishing the year as World No.1, which she described as "really exciting" - considering that it had not been a goal. "It certainly wasn't something that was in my realm at the start of the year," she said. "First and foremost, we'd love to finish off the week here really strongly, then we can worry about celebrating that little thing. Very, very cool for myself, my team. The amount of work and effort we all put in, it does take a village. I have an incredible team of people around me. I think this is more for them than for me."