Coco Gauff held her nerve to beat Elina Svitolina in a gruelling three-set final on Sunday to retain her Auckland Classic title in an ideal warm-up for the Australian Open.

The world number three and top-seeded American demonstrated her grit by fighting back to win 6-7 (4/7), 6-3, 6-3 against the Ukrainian second seed, whose participation had been in doubt after limping through her semi-final the night before.

But Svitolina fully tested the US Open Champion for the first time in the tournament, with 2023 Auckland winner Gauff dropping her first set in two tournaments in the New Zealand city.

"This is the first time ever having to defend a title so I'm really happy I was able to do it today," said Gauff, who won her maiden Grand Slam title in New York in September.

The 19-year-old Gauff was drawn into a thunderous baseline battle against the world number 25, who showed no sign of the back and ankle injuries that affected her in the three-set semi-final win over China's Wang Xiyu.

Svitolina only returned to the circuit in April last year after having a baby.

"I'd like to congratulate Elina for an incredible week," said Gauff ahead of travelling to Melbourne for the first Grand Slam of the year which begins in seven days' time.

"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."

Svitolina, a three-time Grand Slam semi-finalist, broke back twice in a topsy-turvy first set before taking it on a tiebreak.

Gauff began to find her range as she levelled the match in the second and as her confidence grew her unforced error count reduced.

Gauff, who had been barely extended in her run to the final, finished the stronger to take the only break of the third set and pick up an eighth WTA title in 2hr 35min.

"It's been a really great experience to play for the first time here," said Svitolina.

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