Djokovic outlasts determined Federer in rollercoaster Aus Open semi-final

World No. 1 Novak Djokovic has won his way through to his seventh straight Grand Slam final on Thursday, after he defeated a gallant Roger Federer in their Australian Open semi-final: 6-1, 6-2, 3-6, 6-3.

In what will go down as another grueling tussle between the two players, Djokovic looked like taking the match easily in straight sets after jumping to a quick, 3-0 lead from the outset.

The reigning champion then cruised his way through the first set in just 22 minutes, before consolidating in the second to take a commanding 6-1, 6-2, lead after just under a hour.

But, in typical Federer fashion, the Swiss 17-time Grand Slam champion regained his composure in the third, doggedly exchanging service games before he forced a number of break point opportunities when up 3-2 on serve in the third.

Federer squandered a couple of chances, but with parochial crowd support behind him, managed to break for the first time in the match to take a 4-2 lead, consolidate to 5-2 and eventually 6-3 to win the third set.

However a controversial decision to close the Rod Laver Arena roof between the third and fourth sets might have cost Federer his chance at a further comeback; had play not been stopped for ten minutes, Djokovic might not have had time to regain his composure, and Federer's adrenaline levels might not have subsided as much as they did.

As expected following the delay, the world No. 1 fought back in the fourth, forcing an eventual break at 4-3 up.

Despite a staunch last Federer effort, including what could be the shot of the tournament- a flashy down-the-line backhand after being run ragged by Djokovic - the Serb closed out the match not long after, securing his place in his sixth Australian Open final.

With the win, Djokovic now leads the head-to-head record against Federer, having split the previous 44 matches at 22 apiece.

The No. 1 seed said he had to pull out all stops to take down a resurgent Federer.

"I played unbelievably in the first two sets, but that's what is necessary against Roger. He has been playing a high level this tournament," Djokovic said post-match.

"I came up with the right intensity, good concentration and executed perfectly."

The five-time Australian Open champion said he felt as though he was hitting the peak of his career as the likes of Federer and Nadal begin to slow down with age.

"I worked myself very hard to get myself in a position to challenge (players like Federer and Nadal). It wasn't easy but I feel now I'm hitting the peak of my career," he told the crowd.

"In the end of the day it's important that your convictions are stronger than your doubts."

Djokovic will have to face one of Andy Murray - whom he has beaten in Melbourne four times, three times in the final - or Milos Raonic, who has never made a Grand Slam final, on Sunday.

"(Tomorrow's semi-final) is going to be a great match. I think Milos improved his serve and baseline in the offseason. He won Brisbane and is very confident, and Andy is a great player who enjoys great support here," Djokovic said.

Earlier, women's world No. 1 Serena Williams has moved to within one win of clinching her seventh Australian Open title, after she easily disposed of Agnieszka Radwanska in their semi-final: 6-0, 6-4.

Chasing her 22nd Grand Slam title - a feat which would place her alongside Steffi Graf as the most successful woman in the Open era - Williams said she was in rare touch leading into the final.

"I think I played well, especially in the first set, I was able to do everything I needed to do and hitting all the right shots with little to no errors," Williams said.

Meanwhile Radwanska said she was awe of the world No. 1, telling journalists that it would take something special to beat her in the final.

"It is inspiring, especially (considering) I have had very good run, I have so many good matches coming here," Radwanska said, "Then you go on court and you lose 6-0 in 20 minutes. That's not what you expect."

"Everything was just too good. Her serve... you cannot do anything."

The American will face first-time Grand Slam finalist Angelique Kerber in the final on Saturday evening, after she outlasted British hope Johanna Konta in straight sets: 7-5, 6-2.

The left-handed German was ecstatic post-match, telling the crowd it was "a really special moment".

"Reaching the final for the first time, it's special," Kerber said.

"I'm looking forward to playing Serena in the final. It's just amazing to play against the No 1 in the first Grand Slam of the year.

"It's a challenge but I look forward to it. I must play my best tennis to beat her. I have nothing to lose on Saturday."

The women's final will take place in Melbourne on Saturday evening, while the second men's semi-final between Murray and Raonic will be played on Friday evening. Endit