Last updated on .From the section Tennis

2018 Australian Open Dates: 15-28 January Venue: Melbourne Park Coverage: Watch highlights on BBC Two, the BBC Sport website and app. Live commentary on the best matches on BBC Radio 5 live, 5 live sports extra and online.

World number one Simona Halep produced a superb performance to beat Karolina Pliskova in straight sets to reach the Australian Open semi-finals.

The Romanian, 26, won nine games in a row from 3-0 down in the first set as she went on to triumph 6-3 6-2.

Halep will face Angelique Kerber in the last four after the German thrashed Madison Keys 6-1 6-2 in 51 minutes.

Keys, a 2017 US Open finalist, struggled badly throughout, winning only 18 of 46 points on her serve.

Halep said: "It wasn't my best start but I knew I had to restart and move better, which I did in the end."

Halep turns it around

The turning point of Wednesday's second women's quarter-final came in the fourth game, when Halep served three double faults and Czech Pliskova had a break point to establish a 4-0 lead.

After four deuces, the Romanian eventually got on the board and took control from there, showing plenty of aggression as she hit 20 winners.

Pliskova could find no answers and her confidence ebbed away, winning less than 50% of points on her own serve.

Looking ahead to Thursday's semi-final, Halep said: "It will be a different challenge against Angelique Kerber. I have to be ready, be calm and try to dominate the match.

"I'm not thinking about the result. I just want to play my best."

Kerber continues winning run

Angelique Kerber is the only Grand Slam champion left in the women's singles draw

The Kerber-Keys quarter-final was even more one-sided, with the German making it 14 singles wins out of 14 so far this season, including the Hopman Cup team competition.

Keys, seeded 17th, had served 26 aces in her first four matches in Melbourne but did not manage one against the 21st seed.

Eight unforced errors in the first three games set the tone as Kerber raced through the first set and established a 3-0 lead in the second.

Keys broke to love to get back on serve at 3-2 but an errant forehand meant she fell behind again, and Kerber closed out the victory by breaking the American for the sixth time.

"Every game was close in the second set. I am just pleased to get through and be again in the semi-finals here," said Kerber.

"I really enjoy my tennis right now."