Jonathan Jurejko
BBC Sport at Melbourne Park

The roof is closed on Laver! But not because of the stifling heat. Only to showcase the traditional pre-match light show in all its glory.

Someone will press the button soon to get the gears on the retractable roof going.

The good news is we can see Roger Federer and he looks as though he's heading on to court...

Russell Fuller
BBC tennis correspondent at Melbourne Park

It's an extraordinary rivalry. It's gone very much Djokovic's way in recent years. In the last 12 meetings, three quarters of them have been won by Djokovic. The Wimbledon final could not have been any closer but when it really matters, Djokovic has been the winner in recent years.

Novak Djokovic on Roger Federer: "He is one of the all-time greats and the match-ups against Roger and Rafa have made me the player I am today.

"You know he's always going to play at such a high level, regardless of the surface."

Novak Djokovic has had a much easier route - he hasn't dropped a set since his opening round match.

He's spent 10 hours 11 minutes on court and has barely looked troubled as he bids for his eighth Australian Open title.

The Serb has won 10 of his last 11 Grand Slam semi-finals. His last defeat came at the French Open last year, courtesy of Dominic Thiem who knocked out Rafael Nadal yesterday.

Russell Fuller
BBC tennis correspondent at Melbourne Park

Roger Federer has his matchday kit on which will be a relief for everybody. Here comes Rafael Nadal too, so he must know they are playing.

Roger Federer on Novak Djokovic: "Novak also has gone on all these runs like I did for 10 years. He did the same for the last 10 years.

"I think conditions suit us well here. Start the year strong. Probably something to do with court speed, feeling comfortable down here.

"It helps when you start the year off with a bang like he did at the ATP Cup."

David Law
BBC Radio 5 Live Sports Extra tennis commentator

I loved hearing how overwhelmed Sofia Kenin was by it [the win] and how much it meant to her. The players sound so self-assured most of the time and carry themselves in a focus bubble, then you see it all come out - years and years of dedication and hoping they will be in a position like this. She beat the world number one to do it.

As always, send in your thoughts on the tennis. Can Roger Federer carve out another win or will Novak Djokovic prove too much?

BBC Radio 5 Live Sports Extra

There's commentary available of today's match - click play at the top of this page to listen.

Roger Federer has spent 12 hours and 38 minutes on court so far in Melbourne.

It hasn't been easy for him - he had to save seven match points in his last outing against Tennys Sandgren after taking a medical time out on a groin injury.

He beat Djokovic in their last outing - a straight-set encounter at the ATP Finals - but it was Djokovic who came out on top in their epic Wimbledon final last year.

Russell Fuller
BBC tennis correspondent at Melbourne Park

You would have thought by now that Roger Federer has made a decision on whether he is going to play. I assume he knows and Novak Djokovic will have been the first person to be told. We will know soon.

The winner of this men's semi-final will take on either Dominic Thiem - who stunned Rafael Nadal in the quarters - or German seventh seed Alexander Zverev.

David Law
BBC Radio 5 Live Sports Extra tennis commentator

Generally speaking, Roger Federer is not too bothered about the heat. The biggest problem is whether he is fit enough. There are a lot of rumours that he is not.

Roger Federer has won his last two Australian Open semi-finals against Stan Wawrinka and Hyeong Chung respectively, but Novak Djokovic offers a different test today.

The Australian Open is Djokovic's most successful Slam. He has an astonishing 73-8 win-loss record in Melbourne and he has never lost a last four match here.

If Djokovic beats Federer and goes on to win his eighth Australian Open title, he will place Rafael Nadal at the top of the world rankings.

Image source, Getty Images

When these two first met, Novak Djokovic was a qualifier in Monte Carlo, and Roger Federer was the world number one.

Some things have changed and quite a few things haven't...

Image source, Getty Images

Image source, Getty Images

It's the biggy.

Our attention is turning to today's men's semi-final which sees 20-time Grand Slam champion Roger Federer take on the defending champion Novak Djokovic.

Tasty.

Image source, BBC Sport

Andy Lapthorne was beaten in straight sets by world number one Dylan Alcott in the Australian Open quad wheelchair singles.

The British second seed, playing his second match in the round-robin format, lost 7-5 6-1 in Melbourne.

He managed his only break of serve to level the first set at 5-5 but Australian Alcott took control and won eight of the last nine games.

Lapthorne had defeated David Wagner in his opening match on Wednesday.

Image source, Getty Images

Meanwhile, in good tennis news...

Britain's Joe Salisbury is through to his first Grand Slam final after he and Rajeev Ram won their men's doubles semi-final at the Australian Open.

The 11th seeds beat Alexander Bublik and Mikhail Kukushkin of Kazakhstan 4-6 6-3 6-4 on Margaret Court Arena.

Salisbury and American Ram got the decisive break at 4-4 in the final set when Bublik served five double faults.

They will face Australian wildcards Luke Saville and Max Purcell in the final on Sunday (04:00 GMT).

Image source, Getty Images