Spaniard Garbine Muguruza, a relative unknown, overcame her nerves to send former world No 1 Caroline Wozniacki crashing out of the Australian Open on Saturday, continuing her stellar run of form.

The 20-year-old won her first WTA title with a victory over Czech Klara Zakopalova at this month's Hobart International, an achievement even more impressive in that she was a qualifier.

She didn't drop a set from the qualifiers to the final and has stayed on a roll at Melbourne Park, coming from a set down to send the 10th-seeded Wozniacki packing 4-6, 7-5, 6-3.

"I worked really hard in the offseason and this form is the result of that," she said, admitting she was nervous in her first Grand Slam third-round match.

"I was really nervous; it was the third round of a Grand Slam and against a great player. I was only thinking about being aggressive and not being scared."

Wozniacki, recently engaged to golf star Rory McIlroy, remains in search of a first major title despite finishing 2010 and 2011 as world No 1.

She said there were no excuses against Muguruza - she simply failed to take her opportunities.

"Sometimes it happens ... you just don't take your chances. I don't think I did anything particularly wrong," she said. "I thought she played some great tennis. I was just a bit unlucky."

Muguruza's reward is a fourth-round clash with Polish fifth seed Agnieszka Radwanska, who came through three sets against Russia's Anastasia Pavlyuchenkova.

"I will play the same against her," said Muguruza. "I'll be aggressive and just try to do my best."

Muguruza's Hobart win saw her sprint up the rankings to a career-best 38 after right ankle surgery after Wimbledon that sidelined her for the rest of the year.

Wozniacki tipped her to be a force in the future.

"Yeah, definitely she's a good player; she has beaten good players before," she said.

"She's on a roll. I think we'll see a lot of her in the future."