RIO DE JANEIRO (AP) -- Rafael Nadal is back - and it's all about his back.
Top-ranked Nadal injured his back warming up for the final of the Australian Open almost three weeks ago, eventually losing against Stanislas Wawrinka - a match he was an overwhelming favorite to win.
Nadal has practiced little since then, getting treatment at home in Mallorca. His first test comes in next week's Rio Open, a new stop on the ATP Tour.
''We'll have to see how it goes,'' he said Friday. ''I hope I can tolerate it.''
Nadal knows the clock is ticking. He made a comeback last season from a left knee injury, which kept him out of the 2012 London Olympics.
He's won 13 Grand Slams. He's one behind Pete Sampras, and he's closing in on Roger Federer's record of 17. He's sure one got away in Australia.
''In Australia I lost a good opportunity to add another Grand Slam,'' Nadal said. ''It didn't happen. The opportunities are not infinite. They have an expiration date.''
Nadal has played more than 11 years as a professional, perhaps sustaining some injuries because of his big swings and attacking temperament.
''I heard a lot of times in my career that I will have a shorter career because of my style of game,'' he said. ''I really think it's something that will not happen. If I stopped today, I already will have more than 11 years on tour.''
The Spaniard said he's still motivated, positive about the 2014 season.
''I cannot predict the future for how long I will be here competing well,'' he said. ''I can't say when that's going to end. The only thing I can say is today I feel happy about what I am doing. I am feeling motivation mentally to keep playing, to keep competing well.''
He'll be 30 when the 2016 Rio Olympics begin. He called winning gold in the 2008 Beijing Olympics ''one of the best experiences'' of his career.
''It was a very hard moment for me when I made the decision not to play the Olympic Games in London,'' Nadal said. ''After that, I always say my goal is to arrive to the 2016 Olympic Games here in Rio.''
Stephen Wade on Twitter: http://twitter.com/StephenWadeAP