Simona Halep again demonstrated that her injury problems appear to be behind her by beating Karolina Pliskova in straight sets to reach the Sydney International semi-finals.

The world number two withdrew from the Brisbane International in Queensland last week due to an Achilles problem, but saw off Pliskova 6-4 7-5 after overcoming Caroline Garcia in the second round.

Top seed Halep came up with 22 winners and made 33 unforced errors to Pliskova's 43 to move a step closer to winning her first tournament of the year ahead of the Australian Open, which starts next week.

The Romanian raced into a 5-1 lead in the first set and although Pliskova claimed one break back she was unable to mount a fightback, with the favourite then wrapping up the victory despite failing to hold twice in the second set.

Halep said: "It was tough today. It was very close. I was leading in the first set, 5-1, but she came back really strong.

"She did two games in a row at zero - I know she's been playing tough, she's playing well, and she's strong with her serve, and I expected she was going to hit the balls well today."

Halep will face Svetlana Kuznetsova in the semi-finals after the former world number two mounted an incredible first-set fightback and went on to beat Sara Errani 7-6 (7-1) 6-0.

Kuznetsova was 5-1 down in the opening set and saved three set-points before winning four games in a row and then coming out on top in the tie-break. Errani failed to recover, going out with a whimper as she was brushed aside in the second set.

Qualifier Monica Puig surprised home favourite Samantha Stosur 6-4 6-4 and will take on Belinda Bencic in the last four after the eighth seed beat Ekaterina Makarova in three sets.