Rafael Nadal will keep the door open for another Australian summer of tennis, with the 22-time major winner not prepared to declare this his farewell tour.
After almost a year out with a hip injury, the 37-year-old returns at the Brisbane International.
He will meet former US Open champion Dominic Thiem in a likely Tuesday night heavyweight bout after the Austrian scraped through qualifying to reach the main draw.
Nadal said the feeling of being physically ready to compete was what he had missed most.
After a prolonged rehabilitation process that eventually led to surgery in early June, he finally has that feeling back.
"Have I thought about retirement? Of course, yes ... in the low moments it's 100 per cent human," Nadal said on Sunday.
"The problem about saying, 'that's going to be my last season' is that I can't predict what's going on.
"That's why I say 'probably'. It's obvious that it's a high percentage it'll be my last time playing in Australia.
"But if I'm here next year, don't tell me, 'you said it was going to be your last season', because I didn't say it.
"I can't predict how I'm going to be in the next six months and if my body will allow me to enjoy tennis as much as it has in the past 20 years.
"Not in a way to win the most important events, (but) the way that it makes me happy, to feel competitive to go on the court against anyone.
"If I have that feeling, you never know what my approach will be."
Nadal, who last played at the Australian Open in January, initially thought he would miss just eight weeks and not require surgery.
However, he was forced to sit out the French Open - a tournament he has won a staggering 14 times - and was told surgery was the route to his playing return.
"I decided to keep going,'' Nadal said.
"I have the determination, but I know sometimes it will be a painful process."
The two-time Australian Open champion has had lengthy hit-ups with fellow hardened veteran Andy Murray and 20-year-old Dane Holger Rune - Brisbane's top seed who is ranked No.8 in the world.
Both described those sessions as "intense", but Nadal said that description should be taken with a grain of salt.
"You ask my colleagues how I feel and they won't come here and say, 'Rafa is playing a disaster'," Nadal laughed.
"What they say has not much value.
"I don't have the expectations that I used to have, especially for the beginning.
"In terms of practising, I'm quite happy and I feel competitive.
"That's a lot for me because one month ago I didn't know if I would come here and enjoy it.
"Possibly I would come here and go 'I'm not ready'."
