Shenzhen- Maria Sharapova admitted that she needed to play far better after the Russian eased into the semi-finals of the Shenzhen Open on Thursday with victory over Zarina Diyas of Kazakhstan.

The former number one, who has worked her way up to 59 in the world rankings since her return from a doping ban last year, will face the Czech sixth seed and defending champion Katerina Siniakova in the last four in southern China.

The 30-year-old Sharapova, who is unseeded in the tournament that serves as a build-up to the Australian Open, is embarking on her first full season since returning from a 15-month drugs ban in April.

The five-time Grand Slam champion won the Tianjin Open in October for her first title since her ban, but said after defeating Diyas 6-3, 6-3 in 89 minutes: "I didn't play my best tennis and there's certainly a lot of things to improve on in the next (match).

"The great thing is that I'm through and have another chance to play tomorrow."

The other semi-final is between Irina Begu and fellow Romanian Simona Halep, the reigning world number one.

Halep, guaranteed top seeding for this month's Australian Open, blew away Aryna Sabalenka of Belarus 6-2, 6-2.