Fahad Khan:, external Roger needs to win. Probably the last time we will get to witness such a large stage encounter with Nadal. He has a score to settle.

Patrick Alfred: , externalMurray has very nice defences, Federer has good attacks. Tough match to call.

Russell Fuller
BBC tennis correspondent on BBC Radio 5 live sports extra

"Murray won the last meeting between the two and he does have that victory in the 2012 Olympic final. But I think this is one meeting where the past record is less relevant because of what they have been through.

"Federer says he probably won't be 100% fit until March, a legacy of the back problem he had last year and we don't know how Murray will pull up today as he returns from back surgery. But the first week has been encouraging. It's great sitting here genuinely not knowing which way it's going to go."

In Wednesday's other women's quarter-final, Dominika Cibulkova thrashed Simona Halep 6-3 6-0 to follow up her surprise win over Maria Sharapova in the previous round.

Cibulkova will face Agnieszka Radwanska in the semi-finals, with Eugenie Bouchard taking on Li Na in the other last-four match.

Image source, Reuters

In the women's draw, one thing is certain - we'll have a new name trophy after two-time defending champion Victoria Azarenka became the latest big name to be knocked out of this year's tournament.

The 24-year-old she lost 6-1 5-7 6-0 to Agnieszka Radwanska in Wednesday's morning session.

The defeat ended the second seed's 18-match winning run at Melbourne Park and, after Novak Djokovic's defeat by Stanislas Wawrinka a day earlier, means both the defending men's and women's champions are out at the quarter-final stage of the tournament for the first time in the Open era.

BBC Radio 5 live sports extra

We'll have live commentary of Murray v Federer on BBC Radio 5 live sports extra, with build-up starting in just three minutes.

Who is your tip for victory? Get involved on Twitter using the #bbctennis hashtag or if you prefer to tap out a text message, fire it over to 81111 (UK only). The floor is yours.

Rafael Nadal can now kick back in the locker room and watch Roger Federer and Andy Murray fight it out for the honour of facing him in the semi-finals. The organisers are busy emptying the Rod Laver Arena of spectators so those with prized tickets for the evening session can take their spots. That match is set to start at 0830 GMT.

Rafael Nadal is struggling with a nasty blister on his serving hand and the world number one admitted it is affecting his game, "especially with the serve".

He added: "With the serve, I feel the racquet goes. But it's fine. I will try and improve the hand tomorrow and then try to be ready for a tough match against Roger or Andy. It's not a problem in practice, the blister is much better but if I am not playing with protection, it can be much worse."

Image source, Getty Images

"I was so lucky," says Rafael Nadal as he chats to Jim Courier after his four-set victory. "He missed an easy forehand and another one."

The Spaniard was full of praise for his opponent Grigor Dimitrov. "He has everything to become a great champion," he said. "He has a lot of similarities with Roger [Federer], his style. If he can keep playing this way, the normal evolution will bring him to the top."

World number one Rafael Nadal was in a spot of bother out on Rod Laver Arena earlier this morning as Grigor Dimitrov, who is dating Maria Sharapova, had set points to take a 2-1 lead in their quarter-final.

But two forehand errors from the 22-year-old from Bulgaria saw Nadal take the set and from there, Dimitrov's challenge evaporated. The Spaniard winning 3-6 7-6 7-6 6-2.

Image source, Getty Images

Roger Federer, a 17-time Grand Slam champion, has dropped down to six in the world but in Melbourne, the Swiss has been in tremendous form, under the tutelage of Stefan Edberg, winner of six Grand Slams.

The 32-year-old meets Murray, with Ivan Lendl in his corner, for the 21st time, but while he trails the Briton in the head-to-head, the Swiss has won three of their four meetings in the Grand Slams.

Image source, Getty Images

"It's a big match for me," said Murray, after he dispensed with France's Stephane Robert in the fourth round, and he's not wrong.

Murray may well lead the head-to-head 11-9, and boast the last victory between the pair, a five-set corker in the semi-finals at this very tournament 12 months ago.

But has he had enough time on court following his back surgery? Three of his opponents, Go Soeda, Vincent Millot and Robert, are all ranked outside the world's top 100, with Feliciano Lopez, the world number 27, providing his only real test in the third round.

Hello everybody and welcome to the first heavyweight match of the 2014 Australian Open - 17-time Grand Slam champion Roger Federer, who was back to his attacking best in a ruthless straight-sets victory Jo-Wilfried Tsonga in the fourth round, against Britain's Andy Murray, a three-time Australian Open finalist who has looked remarkably nimble in Melbourne so far despite being just two tournaments into his comeback following back surgery last September.

This. Is. It. Andy Murray v Roger Federer and Ivan Lendl v Stefan Edberg. Need I say more?