Simona Halep guaranteed top seeding for this month's Australian Open after battling back from a set down to defeat Duan Yingying 3-6, 6-1, 6-2 in Shenzhen on Wednesday.

The Romanian is now assured to remain world number one ahead of Caroline Wozniacki and Garbine Muguruza for the season's first Grand Slam which begins in Melbourne on January 15.

Looking for a first victory over a top 10 player and cheered on by her home fans, the powerful world number 91 from China blasted her way to the first set without conceding a single break point.

Halep roared back, dropping just three more games to reach the quarter-finals of the WTA Tour event that she won in 2015 after an hour and 37 minutes of action.

"I knew that she's playing hard and hitting every ball, so I knew that I had to be very strong in my legs," Halep said after the match in the southern Chinese city that borders Hong Kong.

"After the first set, I knew I had to find the rhythm a little bit, to stay closer to the baseline and just open the court better, which I did very well.

"It was not easy, even though the scores were 6-1, 6-2. It was a very tough match."

Halep, who posted 21 winners to just 13 unforced errors, will next face another big hitter in teenage sensation Aryna Sabalenka from Belarus.