John Isner claimed his second Auckland Open title with a 7-6(4) 7-6(7) victory over an inspired Lu Yen-Hsun in a tight final at the Australian Open warm-up event on Saturday.

The tall American, ranked 14th in the world, crashed down 23 aces but it was always going to take more than just his big serve to corral the Taiwanese, who put on a brilliant display of shot-making from around the court in his first ATP final.

While Lu ultimately came up short in his first final, Spanish qualifier Garbine Muguruza hammered Czech Klara Zakopalova 6-4 6-0 in hers to clinch a maiden WTA title at the Hobart International.

Ranked number 62 in the world, 30-year-old Lu ended David Ferrer's three-year reign as champion in Friday's semi-finals but Isner held his nerve when it mattered to edge two tiebreaks and avoid another upset.

Lu saved one match point with a brilliant backhand down the line and another when Isner went long with a forehand but, on the third, was unable to get enough racket on a thunderous serve from the American.

"I played exceptionally well today and I needed every bit of it to come out on top," said Isner, who is seeded 13th for Melbourne Park and meets a qualifier in the first round.

"It was close like all my matches this week but I got more and more comfortable the more I played on this court," added the American, who also won the Auckland crown in 2010.

TEARS

In the Hobart International, Muguruza took 70 minutes to wrap up her first title. The tall 20-year-old's dominance and aggression reduced her experienced opponent to tears of frustration in the second set of the 70-minute contest.

It was the second day in a row that a qualifier had won her first WTA title at an Australian Open warm-up tournament after Bulgarian Tsvetana Pironkova claimed the Sydney International women's title.

"I can't explain in words how happy I feel," Muguruza said after receiving her trophy. "Last year I was injured for six months and it's amazing to be here.

"I won my first doubles title in Hobart last year so I guess I'm in love with Hobart now."

Muguruza failed to drop a set over the entire week and her first round opponent at Melbourne Park, 24th seed Kaia Kanepi, will have her work cut out on Saturday's evidence.

The world number 58 clambered all over Zakopalova's service, reducing the Czech to a 33 percent and 41 percent success rate on her first and second serves.

It was appropriate then that, having burst into tears at the final handover and fended off one match point, the 31-year-old should concede the match with her third double fault.

Later on Saturday, world number five Juan Martin Del Potro meets Australian defending champion Bernard Tomic in the Sydney International men's final.