SHENZHEN, China - New city, same result: defending champion Elina Svitolina's campaign at the Shiseido WTA Finals Shenzhen is off and running.

The No.7 seed beat No.2 seed Karolina Pliskova in the first match out of the Purple Group on Monday, needing nearly two hours to secure a 7-6(12), 6-4 victory.

As It Happened: Elina Svitolina wins longest tiebreak of 2019 to stun No.2 Pliskova

After coming from an early break down in the opener, Svitolina survived a titanic tiebreak, in which she ultimately needed seven set points to win the set, and saved one against her. 

"You tell yourself to stay in the moment. You just try to play one rally at a time, to don't rush. Even when I had the chances to finish the set, because there was few, I thought I could play better," Svitolina revealed after the match.

"You just have to quickly restart and just try to take one point at a time, don't rush and don't get down on yourself.

"I had to really mentally be tough, try to don't think so much because obviously she's a great player. I had to expect that she would step up her game.

"Some of the shots were really amazing. What I had to do, I had just to try to get another chance, try to get the point going and to find my way into the match. She was serving couple of times for the set. It was tough.

"I always know when I am tough mentally, I get another chance."

The Singapore champion wrapped up the match in a similarly lengthy second set, where she saw an early break of her own slip away, only to win four of the last five games to wrap up her fourth straight victory against the former World No.1.

Svitolina has not lost to Pliskova in two-and-a-half years, after losing the first five meetings between the two from 2011 to the first month of 2017, and also beat the Czech in the round-robin stage last year in Singapore. 

"I think I became more complete player. I started to play much better. I'm mentally stronger," she assessed of her turnaround in the head-to-head.

"I don't really think about those head-to-heads. I know I'm more consistent now than the game what I was before when we were playing. I think that's what's gives me those wins."

From 0-2 down in the second set, Pliskova won three straight games to take her first lead of the set, but dropped serve at 3-3 to put the Ukrainian back in front.

Tested on serve in the last two games to seal the win, Svitolina held her nerve from 40-0 up in the eighth game, ultimately holding from deuce, and saved two break points in the last game to wrap up the match.

By virtue of winning in two sets, the No.7 seed now tops the Purple Group, which also includes Wimbledon champion Simona Halep and US Open champion Bianca Andreescu. 

"There is always pressure I would say because you see last year, I won two matches, then I had to win one more set. I almost lost the match, almost [was] not qualified for the semfinals," she said.

"There is always pressure. You always have to be up there, always have to bring your best game. Until the last point is done, you have to fight for every single point, every single game.

"That's why round-robins are extremely tough, because you never know what's going to happen. You have to give everything each time you step on the court."

The lone member of the elite eight to not reach a final in 2019, but the defending champion has her eyes on similar success to close out her season. 

"I think biggest motivation is to get the trophy this year. This is my last chance. I try to win as many matches as I can. That's the biggest motivation for me," she said.

"I always try to bring my best game. Just to be here it's already amazing achievement for everyone. Everyone is a champion. You have to bring your best game."