Rafael Nadal hopes to make a comeback to the tennis circuit at the Australian Open, while revealing his pain at missing the London Olympics.

The Spaniard has not played since losing in the second round of Wimbledon, due to a knee injury, but is hopeful of a return at the first Grand Slam of next year.

"All that is in my mind is to keep working hard to come back," Nadal told the Daily Mail. "I cannot think about the future because it's not like if you break your arm and you know you will have a few weeks like this, then a few weeks like that and then you are back. This is a day-by-day thing, I have checks every week to see how I'm improving. I can't predict what will happen.

"I hope you see me in Australia. That is the biggest goal for me, to come back just before then in Qatar, but I cannot say for sure it is going to happen.

"The only thing is to recover well. I want to be 100 percent when I come back. I don't want to keep playing every day with doubts, not knowing if my knee is going to answer all the questions."

The Spaniard admitted missing the Olympics, where he was the defending champion, was pretty tough. "For me the Olympics was very tough. I was very, very sad for three weeks around then. I had the chance to carry the Spanish flag. It only comes every four years. Missing the U.S. Open was hard, but you think you will have more chances.

"The Olympics is once every four years and you don't know how many more you will get. I will work very hard to be in Rio but it is in four years. I am 26-and-a-half, I love competition, playing tennis, and this was actually a season I enjoyed playing more than others.

"I have the motivation to come back and that's what I'm going to try."

Nadal also congratulated Andy Murray on winning his first Grand Slam title at the U.S. Open. "You know I've said many times in press conferences that Andy would win a Grand Slam and now he has won," Nadal said.

"He deserves it more than anyone. I am very happy for him. The normal thing is that it will help him. When you are winning tournaments like this your confidence is higher, it is easier to repeat what you've done before. It's good for tennis that he has come to the level that was expected."