We are up and running once more.

Brutal rallies, sublime single-handed backhands, deft volleys...

Thursday's semi-final was also a belter with Roger Federer coming out on top against his fellow Swiss in five compelling sets.

Here are the highlights (for UK users only).

A hold-up in play, with Rafael Nadal preparing to serve to stay in the set, after a spectator falls ill and needs treatment.

Nadal jogs to the back of the court to jig and flex. Dimitrov stays by his stool, stretching off and puffing his cheeks.

More assistance is on its way to the stricken fan. No sign of the match restarting just yet...

Grigor Dimitrov is under the cosh at 15-30 down.

Twice Rafael Nadal's radar proves a little wonky, just straying beyond the lines.

Dimitrov's turn to mis-cue, planting a backhand between the trams.

Not the highest quality game and it rumbles to deuce before Dimitrov sees off the danger.

Image source, Getty Images

There is nothing the Australian Open crowd love more than some competent hand-eye co-ordination.

Every time a stray ball is cleanly caught by a fan in the stands, they get an appreciative ripple of applause.

Rafael Nadal earns the same as he plucks a Dimitrov return to an 'out' serve from the air.

You'd expect him to pouch it though really wouldn't you?

The Spaniard holds to 15.

Image source, AFP

Simon Briggs
Daily Telegraph tennis correspondent on BBC Radio 5 live sports extra

We've been writing about the prospect of having Federer, Nadal and the Williams sisters in the finals for about a week.

You felt a little bit shame-faced because there was such a long way to go, but you had to because it was the only thing people were talking about.

David Jones: Whoever makes it to the final is going to have to do a better job on serve than this. Federer been holding very comfortably.

Bond Lady: The problem for Grigor is...even if he takes second, you can't write off Nadal. He has such mental strength that he is superhuman.

Derek Thrower: Too many errors from Nadal now. Age catching up with him against the younger man.

Rafael Nadal misjudges a Dimitrov forehand, thinking it is flying long. 

Instead is catches the back of the baseline for 30-15.

These margins are too tight to be trusted. 

Dimitrov unfurls one of those pin-up one-handed backhands down the line and is over the horizon and out of sight.

Nadal serves to stay in the set next.

Image source, AFP

Simon Briggs
Daily Telegraph tennis correspondent on BBC Radio 5 live sports extra

Dimitrov hasn't lost a match this year and you shouldn't underestimate what a factor that could be in a tight match.

Rafael Nadal's service game blurs past like the Tokyo-Kyoto express. A hold to love.

A confident step along the tightrope as we get to the pointy end of things in this third set.

Image source, EPA

This match is more fun than Blackpool's Big Dipper...

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Grigor Dimitrov motors to 40-0. Rafael Nadal provides a small speed bump with a backhand job down the line, but a Hammer-of-Thor ace from Dimitrov closes out the game.

The Bulgarian is not going anywhere.

Image source, EPA

Turns out a few people, like young Charlie earlier (see 10:42), aren't concentrating on what they should be...

Alie Pickwell: Nadal vs Dimitrov. When tennis is more interesting than writing a thesis.

Jake Dilley: This could go the distance. Nadal and Dimitrov keeping me entertained at 'work'. Come on Grigor lad! 

Adam White: Not getting any work done today. My computer is fixed to BBC Sport website.

Classic old-school serve-volley from Rafael Nadal scrapes a third break point off the table.

But here comes a fourth with Dimitrov slapping a winner down the line.

Nadal goes on the attack, but he has asked too tight an angle of his forehand. The top-spin doesn't bite hard enough and we are back on serve.

Image source, AFP

It is open house on the serve at the moment.

A Rafael Nadal double-fault gives Grigor Dimitrov a free leg-up into the game. 

The lactic is starting to flow now. Another slug-fest baseline exchange ends with Nadal straying wide.

Nadal is battered into submission on the next point as well and two break-back points to play with for Grigor Dimitrov at 15-40.

Nadal saves both. But he is not out of the woods yet. Deuce.

We can't call this one. Can you?

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Grigor Dimitrov - with acres of open court to aim at - over-cooks to offer up a break point at 30-40.

Creaky times for the Bulgarian.

And he concedes the break as he pushes long on a nothing-much backhand.

He started this set the stronger, but the underdog is chasing once again.

Image source, Getty Images

Choudhary Sab: Just how similar is Grigor's game to Roger's? That single handed backhand down the line is serene.

Paul McG: This is not the Nadal of his peak and if it was he would wipe the floor with Dimitrov.

Obbby: Tennis ; compelling, gladiatorial, demanding, awe-inspiring, play deep into old age, invigorating ! The best sport bar none :) 

Old age, Obbby? Hitting your thirties isn't THAT old you know...

Image source, EPA

Simon Briggs
Daily Telegraph tennis correspondent on BBC Radio 5 live sports extra

Are we watching tennis or gymnastics? Dimitrov has this flexibility to be able to do the splits and he stretches this way and that during rallies. If an ordinary mortal attempted it they'd probably be in a cast for six weeks.

Image source, Getty Images

Rafael Nadal gets stung by the Grigor Dimitrov forehand as the Bulgarian socks a forehand winner down the line for 15-15. Nadal did not bother getting out of the blocks for that one.

Anything you can do though...

Nadal smears the paint with a crushed forehand and then puts away a volley for 40-15.

Another dreamy Dimitrov backhand brings up 40-30.

Dimitrov shows the flexibility of a yoga seventh dan as he is forced onto the defensive in a hum-dinging 19-shot rally. Finally he succumbs and the Rafa serve is safe.

Image source, EPA