Daria Kasatkina is having trouble with Serena Williams' power. Who doesn't?

The American again races through a service game to love. An ace, a thunderous volley at the net and an unreturnable first serve. Awesome.

Kasatkina has a sweet shot on her.

A forehand off the middle of the racket is a winner out right but a double fault brings it back to 15-15.

A very tentative second serve is given the treatment by Williams, a ferocious forehand winner, and the Russian then goes long to give two more break points.

Both are saved, as she holds her nerve from the baseline - forcing Williams into a couple of errors - before a kick serve at advantage wins her first game.

The fun tennis players have eh?

Let's hope he's not all at sea tomorrow... (sorry).

So Seppi did win a game in the end. And then Djokoic put him out of his misery to claim the first set. Not even a contest at the moment... 

This could be a long match for 18-year-old Dari Kasatkina.

Two big first serves from Serena Williams and it's 30-0.

The Russian sends a forehand long to hand Williams game point and a booming ace down the middle - after a challenge - seals the game.

Perfection.

What power from Serena Williams. A thunderous service return flies past the Russian and obviously rattles Kasatkina.

Two double faults follow and Williams breaks.

The biggest match of Daria Kasatkina's  life and she wins the first point as Williams sends a forehand wide.

The Russian nets with a lazy-looking backhand to bring her opponent level but is trading well early on as she forced the American into another error. 15-30.

Brilliant from Williams though as he slams a forehand winner into the corner, before reaching a smart drop shot to move 40-30 up.

Big first serve and a follow up smash at the net. Game Williams.

Time is called.

Serena Williams, dressed in a brilliant yellow, to serve.

Here we go.

Novak Djokivic is making very, very short work of the first set against Andreas Seppi.

He is 5-0 up.

Looks like the world number one is racing into the fourth round.

In contrast, Serena's opponent, Daria Kasatkina, is at the start of her career.

The 18-year-old from Russia is in only her second ever grand slam, reaching the third round in the US Open in 2015.

She did beat Serena's sister, Venus, at the ASB Classic earlier this year though and is tipped for big things...

Is Serena Williams the greatest female player ever? John McEnroe thinks so.

The American has 21 major titles to her name, held all four grand slams at one point last year, and is showing no signs of slowing down.

She has six Australian Open titles to her name - including winning in 2015.

Can anyone stop her? They are out on court.

Maria Sharapova's three set win over unseeded American Lauren Davis was the 600th win of her career.

World number one Novak Djokovic is already underway on the Margaret Court Arena against Andreas Seppi.

He has a break and is 3-0 up in the first set.

Not bad is he?

Image source, AP

What has already happened?

Roger Federer reached the last 16 at the Australian Open after proving too strong for Grigor Dimitrov in their highly-anticipated third-round match.

The Swiss third seed won 6-4 3-6 6-1 6-4 under the Rod Laver Arena roof as rain halted play on the outside courts.

It brought four-time champion Federer his 300th Grand slam match win.

Former champion Maria Sharapova was also able to progress,  beating unseeded American Lauren Davis 6-1 6-7 (5-7) 6-0.

Image source, .

Some sad news yesterday.

Former BBC television and radio tennis commentator Gerald Williams has died at the age of 86.

The Welshman was part of BBC Sport's coverage from Wimbledon along with the corporation's ex-presenter Des Lynam.

"Gerry was one of the finest tennis commentators of our time," said Barbara Slater, director of BBC Sport.

"His famous Wimbledon commentary and his on-screen partnership with Des Lynam will be remembered with fondness by everyone at BBC Sport."

With all that mind, today's final match of the night session on Rod Laver Arena should be a classic - as Nick Kyrgios looks to upset Czech sixth seed Tomas Berdych.

We will bring live coverage of the third round match later but first, a tasty appetiser.

World number one Serena Williams plays Russia's world number 69 Daria Kasatkina - and it might not last that long.

We bring you that first.

Image source, EPA

Yes, hello again.

Nick Kyrgios has got a long way to go before he is mentioned in the same breath as compatriot Lleyton Hewitt.

The "bad-boy" of tennis has attracted as many headlines for his behaviour as he has for his ability - with fines and warnings common place in the 20-year-old's fledgling career.

With Hewitt gone though, Australia is looking for a new hero. Time to step forward Mr Kyrgios?