Rafael Nadal of Spain attends a pre-final news conference at the Australian Open tennis tournament in Melbourne January 28, 2012. (Photo:REUTERS)
Nadal, who will play Novak Djokovic in Sunday's title match, said Murray could be crowned world number one this year and was "unlucky" not to have won a grand slam.
But he highlighted a weak fourth set in Friday's epic, near five-hour clash with Djokovic, when Murray threw away a two-sets-to-one lead. The Scot fought back in a nail-biting fifth but he cracked when serving to stay in the match.
Spain's Nadal, a 10-time grand slam winner, said it was an opportunity missed for Murray, who is seeking to end Britain's 76-year wait for a major men's title.
"Yesterday he lost another very good opportunity, in my opinion," Nadal said. "To win a tournament like this and to play against a player like Djokovic, you cannot start the fourth set like this.
"It's the moment to play with more intensity than ever, not start with 3-0 down and two breaks in five minutes. That way you lose the match.
"You want to win the tournament, the other can beat you, but you cannot lose in the beginning."
Murray took pride in his performance, after his straight-sets hammering by Djokovic in last year's final, and said he was closing the gap on the top three, who also include Roger Federer.
But Nadal said fourth-ranked Murray was "never very far" from the leading trio, who have annexed the major titles and the top ranking in recent years.
"He's playing well. He's playing fantastic. He deserves to win a grand slam," Nadal said. "He was unlucky at the end, but the only negative thing for me in his match is the beginning of the fourth.
"When the other have more doubts, you make it easier for the opponent than it should be, no? That's my feeling.
"For the rest, he can be number one at the end of the season. I don't have any doubt on that. The level is there. When you are able to play five grand slams in a row playing semi-finals or finals, it's only a mental thing."
"The rest of the things are there…. He's ready for everything."
Murray also said he was ready to take the next step, after reaching his fifth consecutive grand slam semi-final and being on the losing side in three major title matches.
"I think there's a very fine line between being number one in the world and being three or four. I think that gap, I feel tonight I closed it," he said.
"My job over the next two or three months is to surpass him and the guys in front of me. So it will take a lot of hard work, and hopefully I can do it."
German great Boris Becker, writing in Britain's Daily Telegraph, said Murray had shown that a major title may now not be far away.
"The quality of his tennis certainly suggested to me that he is on the path towards that elusive first major title. The way he is playing, it might happen sooner than you think," Becker wrote.
"Yes, it was frustrating that Andy couldn’t get over the line. But he can hold his head up high after what must be the finest performance I have seen from him. He did almost everything right and the difference came down to the smallest of margins."
And Djokovic said he had noticed a big change in Murray, who is now coached by eight-time grand slam winner Ivan Lendl and has appeared calmer and more resilient on court.
"He was more confident on the court. He was taking his chances. He was being more aggressive. I think he was playing better," said the Serb.
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