Coco Gauff held her nerve to beat Elina Svitolina in a gruelling three-set final of the Auckland Classic on Sunday to defend her title and fire an Australian Open warning shot.

The top-seeded Gauff showcased her grit by fighting back from a set down to win 6-7 (7/4), 6-3, 6-3 against the Ukranian second seed, who was in doubt to even play the match after limping through her semi-final the night before.

Coco Gauff of the USA reacts during her singles finals match against Elina Svitolina of Ukraine at the ASB Classic tennis tournament in Auckland. Photo: photosport

Instead Svitolina fully-tested the US Open Champion, a new experience in New Zealand for Gauff, who clinched last year's title without dropping a set and looked set to repeat that feat after strolling through her first four matches.

Instead the 19-year-old was drawn into a thunderous baseline slogfest against the world number 31, who showed no sign of the back and ankle injuries that plagued her in the taxing three-set semi-final win over China's Wang Xiyu on Saturday.

Perhaps because of her lighter workload through the week, Gauff finished stronger, snaring the only break of the final set in the eighth game.

Elina Svitolina of Ukraine reacts during her finals match against Coco Gauff of the USA at the ASB Classic tennis tournament in Auckland. Photo: photosport

She served out to pick up an eighth career title and the first since her maiden Grand Slam triumph in New York in September.

It was also the first time she has defended a title, something she said was the main motivation for returning to Auckland.

"This is the first time ever having to defend a title so I'm really happy I was able to do it today," she said.

"I'd like to congratulate Elina for an incredible week. What you do, being a mum and coming back so fast and at such a high level is pretty inspiring.

"Hopefully - not any time soon - I'll be able to do it like you've done it."

Gauff said she had enjoyed this year's tournament more than last year's weather-affected event.

"This year's tournament was a lot different. Last year it rained almost every single match with just two or three people watching so it's been really cool to play in front of a packed crowd nearly every single match."

Svitolina, a three-time Grand Slam semi-finalist and chasing an 18th WTA title, showed no sign of the gruelling nature of her week in the first set, twice breaking straight back after dropping serve before clinching the tiebreak.

Gauff broke serve on the first game of the second set but didn't have an easy ride before squaring the match at one set all.

She discovered her rhythm in the third set, removing some of the wayward ground strokes that dogged her earlier in the match.

Svitolina said she had enjoyed the week, which featured wins over former grand slam champions Caroline Wozniacki and Emma Raducanu.

"It's been a really great experience to play for the first time here. I've been really enjoying myself here, playing great matches," she said.

"A tough loss today of course but I'm hoping I can come back next year as well to play more tennis here."

This story was originally published by RNZ