(CNN) -- Rafael Nadal has admitted he is unlikely to play again this year as he set his sights on a return from injury at January's Australian Open.
The former world No. 1 has been sidelined with tendonitis -- inflammation in the knee -- since withdrawing from July's Olympic tournament and has not played since losing to unseeded Czech Lukas Rosol in Wimbledon's second round.
Eleven-time grand slam winner Nadal refused to rule out playing in Spain's Davis Cup final match against Czech Republic in November, but admits it could be difficult to force himself into the team after a three-month absence.
"My biggest goal is to compete at Australian Open," the 26-year-old Spaniard told CNN Espanol, referring to the first grand slam of 2013.
"About the Davis Cup final, of course I would love to take part in it, but first I have to see if I will be ready technically and physically.
"We would have to ask whether I am the right choice to compete in a Spanish team that has been long preparing for this important tie considering also the months I have spent without playing. But that's a decision that it's not mine."
Nadal has won the Davis Cup on three previous occasions, in 2004, 2009 and 2011, but missed out on Spain's 2008 triumph with a previous knee complaint.
"Let's take it one day at a time," added the former world No. 1. "I'd rather be cautious especially after trying to recover for the London Olympics and for the US Open with no success.
"I prefer to go day-by-day without setting objectives or time frames, work hard on my recovery and make sure I keep on getting better little by little."
Nadal has been forced to watch from the sidelines as longtime rival Roger Federer returned to the top of the world rankings after winning a seventh Wimbledon singles title.
He has also seen Britain's Andy Murray, who won the men's singles gold medal at the 2012 Olympic Games, move above him in the world rankings after securing his first grand slam title at last month's U.S. Open.
Currently ranked fourth in the world, Nadal has qualified to play at November's season-ending ATP World Tour Finals in London, but his ability to take part is in doubt due to his injury problems, admitting that his knee is still "bothering him".