Nadal still the puzzle Federer can't solve

Roger Federer barely broke sweat in reaching the Australian Open semi-finals, producing some of his finest tennis at the age of 30. Then he ran into Rafael Nadal - again.

The Swiss did not drop a set in reaching the last four, handing out lessons in sumptuous shot-making to illustrious Argentine Juan Martin del Potro and rising Australian teenager Bernard Tomic along the way.

But despite a dazzling start to his semi-final with Nadal, it was a familiar story when the 16-time grand slam champion crashed out in four sets, making 63 unforced errors with five double-faults.

Federer's record against his grand slam nemesis makes for bleak reading. He now trails the Spaniard 8-2 at majors and has not beaten him on the biggest stage since Wimbledon in 2007.

In overall meetings the Swiss world number three now trails 18-9 and has recorded some significant wins, including at last year's ATP World Tour Finals in London, but it is Nadal who wins the matches that matter most.

Federer, who has claimed the Australian Open title four times, insists the Spanish world number two does not get into his head, although he says Nadal, 25, finds a way to raise his game when they meet.

"We have had good matches over the years. I enjoy playing him. The crowd really gets into it, which is nice. We have a lot of respect for each other, which is good, too, I think," Federer said.

"We also play well against each other. I always think he plays a bit better against me than against other players, but that's good for him."

And Federer, not entirely convincingly, insists the head-to-head record does not bother him.

A glance at his record against other rivals is revealing. He came out on top eight times in 11 meetings with Andre Agassi. He leads world number one Novak Djokovic 14-10. His record against Andy Roddick is 21-2.

But Federer has never come from behind to win a grand slam match against Nadal and Thursday's match on Rod Laver Arena followed a predictable pattern, with Federer's exquisite play breaking down against the unrelenting Nadal.

Revealingly, Nadal said the best-of-five sets format at grand slams made him "more calm", as he knows he'll have time to work his way back into a match.

"When you play indoors, when you play the best of three, he plays aggressive. It is very difficult to come back when he starts like this," said Nadal, who took just three games off Federer at the ATP World Tour Finals.

And the Spaniard dismissed Federer's theory that he saved his best for his great rival.

"I don't play my best tennis because it's Roger in front. I play my best tennis because I'm ready to play my best tennis," he said.

Federer, who came to Australia after finishing 2011 on a 17-match winning streak, was measured after his latest loss to Nadal, saying he hoped to have many more chances to win the title in Melbourne.

But he may have to find a way to beat Nadal first.