A bobble off the net falls favourably for Simona Halep, and brings up break point in the process.

What a return that is! Halep, forced out wide, somehow gets her backhand to skim off the top of the net and bounce right on the line. That's four games in a row for the world number one.

Karolina Pliskova coughs up her first double fault of the match, before she jumps and watches a forehand plonk into the corner of the court.

A 17-shot rally eventually goes Pliskova's way, with Halep sliding her return into the net, but Pliskova picks an inopportune moment to err on her backhand. Deuce.

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Nice. That's much better from Halep, meeting Pliskova's cross-court forehand with a winner of her own.

The serve is clicking now, too, and Halep holds to love.

Oh, and Simona Halep only needs one!

A sensational return catches Karolina Pliskova off guard, and she nets her response. Let's see how that serve is going...

Karolina Pliskova's sliced backhand meets Simona Halep's meaty forehand, and Halep draws two errors out of the Czech.

That'll be two break points to the world number one.

Karolina Pliskova gets Simona Halep right where she wants her, running to her left as Pliskova advances, but she puts too much on the forehand and that's out.

Down the line goes Pliskova, but she nets. Simona Halep is on the scoreboard.

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Simona Halep hoicks down a loose second serve, but Karolina Pliskova slaps it into the net.

That's tremendous from Pliskova though, forcing Halep to sprawl with her backhand, and she nets. Deuce #4.

A smash winner from Simona Halep, with Karolina Pliskova stranded out wide, ends another good rally.

Another double fault! Halep smashes her arm against her thigh in annoyance. That's three in this game, and four in the match...

Big hitting from both players, picking the ball up off the baseline and returning deeply, but it's Karolina Pliskova who blinks first.

Advantage Halep, but her second double fault of the game sees that disappear. Back to deuce we go.

Into the net goes a Pliskova forehand. Deuce.

Karolina Pliskova follows up a real mess of a drop shot with the most leisurely forehand winner - she barely reacts, even when she hits a fine strike like that.

Hmm. Another double fault from Halep squanders a 30-0 lead, and Pliskova pushes her wide and spears a winner past her to secure a break point.

Three big serves in a row from Karolina Pliskova sees her race to 40-0, before a forehand goes awry.

Ooft. Halep responds with an almighty return of serve, crouching low and crashing a backhand winner back. A forehand error ensures Pliskova holds.

It's Angelique Kerber that awaits the winner of today's match, after her speedy win over Madison Keys.

Kerber, who won the title in Melbourne in 2016, dominated the American, winning 6-1 6-2 in just 51 minutes.

The German is doing her upmost to put a terrible 2017 behind her - she hit 13 winners and made just seven unforced errors as she breezed past Keys.

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Hmm. A double fault from Halep and Pliskova takes advantage of the opening, stepping forward to crack a backhand winner into the corner of the court and get herself two break points.

That's long on the forehand for Halep! An early break for Pliskova.

Simona Halep's backhand drifts long, but Pliskova can't take advantage as a forehand just misses the mark.

A rally goes Pliskova's way, Halep moving in to the court and netting her return, and Pliskova's big serve helps her hold.

* denotes next server

Karolina Pliskova, towering over Simona Halep at 6ft 1ins, cracks down a big serve and sends Halep haring around the baseline, before the world number one nets.

A few errors allow Halep onto the board, and the Romanian steps in and whacks a backhand cross-court to force deuce.

Here we go: it'll be Karolina Pliskova to serve first.

The winner will play Angelique Kerber next.

Karolina Pliskova, a former number one herself, has spent two hours less on court than her opponent today.

A first-round win over Veronica Cepede Royg was followed by a demolition of Brazil's Beatriz Haddad Maia, with Pliskova wrapping up victory in 44 minutes.

Compatriot Lucie Safarova was next, but again, the sixth seed registered a straight-set win before having to work a little more against another Czech, Barbora Strycova.

Strycova took the first set but Pliskova - easily one of the coolest customers around - held her nerve to win 6-7 (5-7) 6-3 6-2.

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Top ranked Simona Halep arrived in Melbourne with two titles under her belt, after she won the singles and doubles events in Shenzhen.

Halep rolled her ankle during her first match against wildcard Destanee Aiava but she was able to brush past Eugenie Bouchard next.

A third-round match-up against Lauren Davis was more difficult: the players battled for three hours and 44 minutes, with Halep saving three match points in the decider before forcing a win.

Big-hitting Naomi Osaka was next, but Halep registered a 6-3 6-2 win to reach her third quarter-final in Melbourne.

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Here's how these two line up.