Top seed Elina Svitolina dug deep to book her place in the semifinals of the ASB Classic, outlasting Britain’s Sonay Kartal 6-4 6-7(2) 7-6(5) in a quarterfinal that stretched over two hours and 36 minutes.

In one of the most physically and mentally demanding matches of the tournament so far, Svitolina leaned heavily on her resilience to escape a contest that looked to have swung in Kartal’s favour, before ending in a tense final-set tiebreak.

After the match, Svitolina pointed to her mindset as the decisive factor. “I think the fighting spirit definitely brought me back after the second set, the tie break, and then also, from 3-5 down, it wasn’t easy,” she said. “I think fighting spirit really carried me through the match.”

Kartal pushed the Ukrainian throughout, striking the ball cleanly and repeatedly forcing Svitolina to raise her level.

The top seed was taken to a deciding set after Kartal claimed the second-set tiebreak convincingly, and later found herself on the brink of defeat when Kartal served for the match in the third set.

Svitolina said this was a mental battle as much as a physical one.

“I think it was 50/50, mental and physical, because I had to stay really focused on myself, on the fighting spirit, to stay in the match,” she said.

“Because I could easily have just check out and then the physicality doesn’t matter anymore. So I’m happy the way I could stay in the match.”

Kartal continued to apply pressure in that third set and served for the match at 5-4, before getting broken. In the tiebreaker that followed, Kartal made an error when serving at 4-5 and soon after Svitolina sealed the win on her second match point, ripping a forehand from the back of the court.

Svitolina was quick to acknowledge the challenge Kartal presented. “To be fair, Sonay played a really great match and was striking the ball well,” she said.

“I had to raise my game, try to bring something more than I did from the [other] matches.”

The victory continues a demanding start to the season for Svitolina, who said she expected opponents to lift their level against her.

“I feel my game is here, of course, as the first seed, everybody wants to beat you really badly and they’re bringing their best game,” she said. “I expect this when I go on the court. Of course, it’s not easy, but it’s good to have, because it pushes me.”

Svitolina will play third seed Iva Jovic in the second semifinal on Saturday night.