SHENZHEN, China - No.8 seed and defending champion Elina Svitolina became the first player to qualify for the Shiseido WTA Finals Shenzhen semifinals, winning her seventh straight match at the year-end finale to dispatch No.5 seed Simona Halep 7-5, 6-3 in one hour and 39 minutes.

The Ukrainian had to hold off several patches of irresistible form from Halep, but ultimately - as she has so often in her career - proved the superior match player, able to select and execute the right shots to avoid relinquishing her lead.

"I try to work every single point and start from the beginning just trying to take one point at a time," she explained afterwards of this characteristic. "I don't really think so much about if it's good, if it's bad. Just taking every point, every game at a time. I try to step on the court and to always have positive mindset."

The result avenges two previous defeats at the hands of Halep this season - a thriller in the Doha semifinals and a rather more one-sided contest in the Wimbledon semifinals - and squares their overall head-to-head at five wins apiece (although Svitolina now leads 5-4 at WTA level). With Svitolina having won both of her Purple Group round-robin matches so far in straight sets, the victory also guarantees that she will progress to the weekend's semifinals.

"I don't take it as a pressure, to be fair," said Svitolina - who has successfully defended three titles in her career to date - about the experience of being the previous year's champion. "Of course, there is some kind of pressure because you're losing points in this week. I think this kind of thing is pressure. I always try to never take it that way. I always try to take it as: I played well here, so let's find this year as well. This kind of mindset, this kind of game, it takes work to do it."

Svitolina leapt out of the blocks with the sharper start, hitting her spots with pinpoint accuracy to storm through 14 of the first 18 points, taking a quick 3-0 lead over an error-strewn Halep. But the Romanian did not remain at that level for long: coming up with some brilliant strikes from the forehand wing in particular, Halep hit back to level at 3-3.

But just as it seemed as though momentum might swing fully towards the Wimbledon champion, who held a break point to move up 4-3, Svitolina stood firm to hold off the looming threat. A big backhand strike on the run elicited a netted Halep forehand to stave off the break point, setting the stage for a run of six tightly contested holds as each player attempted to penetrate the other's stellar defence - with mixed results.

At the business end of the set, though, it was Svitolina who sensed the moment to step up. Her hold for 6-5 featured more outright winners than any other game in the set - and set her up for a love break to capture the set as Halep relapsed into error, taking her tally for the set to an uncharacteristic 21.

Despite the tightness of the first set, ground would be even less easily given as the second act began. Both players used every inch and angle of the court in their attempts to out-maneouvre the other - but more often than not it was Svitolina who translated this into scoreboard results. Halep would make the first move, the former World No.1 hammering a clean backhand return winner to go up 2-1 - but Svitolina responded by immediately pegging her back via a three-deuce mini-tussle, finishing with some spectacular defence.

"I felt that I cannot finish the points," a frustrated Halep said afterwards - music to her rival's ears. "I was moving well," smiled Svitolina. "I think every player tries to work for that moment when the opponent has no answer. I know that when I'm fit, I can play very good, I can move very good, I have a good defence. It's about managing attack and defence for me."

From there, the Wimbledon and US Open semifinalist was in the driver's seat: not only did she exhibit her trademark gritty retrieving, but four aces helped her develop somewhat more comfort on serve - and she found one particularly creative way to end an extended rally by chopping a forehand through the court with so much spin that it landed as a clean winner.

"I think many people were surprised - even myself because I played it that well," recalled Svitolina. "Honestly, I actually played many more of these shots when I was growing up. I was lots of slicing. It was actually working a lot for myself because my coach at that time, he really hated that shot. But you see here, it brought me a point, very important one. Surprised the opponent. You never know - it might help me in the future, too."

As in the first set, Svitolina's awareness of when to adjust her tactics according to the scoreboard moment was razor-sharp. A handful of Halep errors in the eighth game opened the door slightly - and, upping the ante, Svitolina pounded through it, breaking to love with a backhand drive volley.

Serving for the match, the 25-year-old had a minor wobble - but Halep was unable to take advantage of two break-back points, and clutch serving ultimately got Svitolina over the line and into the semifinals for the second year in a row, with her position in the group dependent on results to come - while Halep will need to return on Friday to battle for her place in the last four.