Haas will return to the court for the first time since October 2015 as a wildcard at the Australian Open after a long rehabilitation following surgery for a torn ligament on his right foot.
The ligament repair last April was his ninth major surgery, having been under the knife for a litany of shoulder complaints and other problems with his elbows, hips and ankles.
Haas's previous comeback from surgery on a troubled right shoulder was in mid-2015 but it lasted only four months before he was sidelined with the foot injury.
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Rather than feel his body might be telling him something, the aborted comeback only reinforced Haas's determination to bow out on what he called his "own terms".
"I think it's very important for any athlete, it doesn't matter what sport you are in or whatever it is you may do, it's important to find that right time or that moment for you, when you feel it's over, to move on and do something else," he told reporters at Melbourne Park on Sunday.
"It's very important just to be back on tour, back here at the Australian Open, it's been a while since I've played here.
"I'm very excited about the chance to go out on the court one more time ... I've had great memories here.
"As this year goes on ... I'm just very excited to see what's in store for me.
"And then (later) know exactly the right time to say goodbye."
Twice named the ATP Tour's 'Comeback Player of the Year,' in 2004 and 2012, Haas is a three-times semi-finalist at Melbourne Park, the last trip to the final four coming in 2007.
He will kick off his latest return in tough conditions on Tuesday, with a scorcher forecast for his first round match against 47th-ranked Frenchman Benoit Paire.
Named tournament director for Indian Wells last year, Haas has a comfortable retirement waiting but said he still dreamed of going deep at a tournament one more time.
But as the oldest player in the men's draw, he could be forgiven the old cliche of taking it one match at a time at Melbourne Park.
"Now it's really about playing point for point, game for game," he said.
"I'm very stoked about the next opportunity."
(Editing by Peter Rutherford)
