Well there's a turn up...

Not sure if it was a loss of concentration from Novak Djokovic or what, but Botic van de Zandschulp gets one of those breaks back immediately after his medical timeout.

Andy Lapthorne
Six-time US Open quad champion on BBC Radio 5 Sports Extra

Novak Djokovic has full control now and you would have to question how much longer this match is going to carry on if he is going to keep moving the big Dutchman around the Rod Laver Arena the way he is at the minute.

Russell Fuller
BBC tennis correspondent on BBC Radio 5 Sports Extra

The two-time champion Naomi Osaka is out and that's a big blow to the draw.

It's great news for Maddison Inglis at 168th in the world, having come through qualifying, because she is into the fourth round.

What on earth is going on on Margaret Court Arena?

Anna Kalinskaya has just broken Iga Swiatek to love. The second seed's first percentage has collapsed to 44% in the second set and she's won just 13% points behind it. She lost all three service games.

Kalinskaya then races into a 30-0 lead with a pair of sumptuous forehand winners and although she blots her copybook with a couple of unforced errors to waste two set points, she converts the third with a forehand winner.

She's taken the second set 6-1.

Jonathan Jurejko
BBC Sport tennis news reporter in Melbourne

Well, that news has got the media centre murmuring.

Naomi Osaka has decided she is not fit enough to play tonight because of an abdominal injury.

She could not have waited any longer before pulling out of her upcoming match against Australian qualifier Maddison Inglis.

The pair were due on court straight after the current match between Novak Djokovic and Botic van de Zandschulp.

Big problems for Botic van de Zandschulp, who is not only now two breaks of serve down in the second set, but is now receiving fairly vigorous treatment for a right shoulder issue.

What an atmosphere on John Cain Arena!

Stan Wawrinka, already down a break, gives away a 40-15 lead before saving a break point with an ace. He later closes out the hold in similar fashion and the crowd erupts.

Taylor Fritz responds with a hold to love, matching Wawrinka's two aces.

Some breaking news - Naomi Osaka, who was scheduled to be in action after Novak Djokovic on Rod Laver Arena, has pulled out of the Australian Open.

The four-time Grand Slam champion has posted the following on Instagram:

"I've had to make the difficult decision to withdraw to address something my body needs attention for after my last match.

"I was so excited to keep going and this run meant the most to me, so having to stop here breaks my heart but I can't risk doing any further damage so I can get back on the court.

"Thanks for all the love and support... I'm so grateful everyone embraced me so much.

"And thank you to my whole team for always having my back and the tournament organisers for being so kind."

It means Australian qualifier Maddison Inglis will get a bye through to the last 16.

These two need to cool it with the break points. My keyboard is burning up.

Iga Swiatek collects two with a backhand winner at 15-40 but Anna Kalinskaya saves them both to force deuce, including pulling out a timely ace.

She saves a third break point and eventually comes through an iffy hold in the third deuce.

Third set, anyone?

Iga Swiatek has been very erratic early on in this second set. Approaching the net at 15-all, she (somewhat recklessly, in my opinion) takes the ball out of the sky with her racquet shoulder-height and parallel to the ground and shanks a forehand well wide. Why that shot?

Anna Kalinskaya overpowers her opponent with a booming backhand to collect another break point before Swiatek nets a forehand.

Three consecutive breaks.

Another break opportunity for Novak Djokovic at the start of the second set - and he's got a second serve to attack, too.

A wild backhand from Botic van de Zandschulp gifts the game to the Serb, who is in full control here.

Djokovic has shown some moments of class, but has also won a lot of points where he's just stayed in there and allowed Van de Zandschulp to make the error.

Pat Cash
Former Wimbledon champion on BBC Radio 5 Sports Extra

It's almost like Novak Djokovic picked the draw and the weather himself. They've closed the roof for him and it doesn't always work that way in Grand Slams.

If he could have picked exactly his ideal first three matches under certain conditions, he's got them.

Ominous signs for Stan Wawrinka after Taylor Fritz seals a comfortable hold to 15 with his 24th ace before converting his second break point of the set to take an early lead.

Is this the beginning of the end?

Iga Swiatek breaks right back, stepping onto a short ball and firing home a cross-court forehand with both feet off the ground.

We're back on serve on Margaret Court Arena.

Image source, Getty Images

Novak Djokovic has another set point but double-faults, so it's deuce.

The Serb gets it done eventually though, sealing the first set in 42 minutes.

Anna Kalinskaya is not going down without a fight. She opens up the court by dragging Iga Swiatek wide on the backhand side and is quickly up to the net to put away the volley.

Swiatek misses a forehand for 0-30 and although she pulls back the next two points, she gifts a return into the centre of the court and Kalinskaya buries a backhand winner to earn a break point.

She wastes the opportunity with a loose backhand but earns a second with a belting forehand return. And this time she pounces.

Now then.

Stan Wawrinka, fresh off the treatment table, holds to 15.

Taylor Fritz is muttering to himself as he heads to his chair.

Novak Djokovic will be forced to serve it out.

Pat Cash
Former Wimbledon champion on BBC Radio 5 Sports Extra

It's a great match-up for Novak Djokovic because the first couple of rounds have been quite decent draws for him.

Here, he's got a player who has got a clear weakness that he can exploit and when he needs to, he can just go out to the forehand and look to get an error.