Chalmers will tee off with modest hopes on Thursday in what will be the US PGA regular's first tournament since last year's Open at The Lakes.

But he already feels like a winner having overcome debilitating injury just to make it back.

"I had arthritis in all five joints in the lumbar spine and a torn ligament," Chalmers told AAP on Tuesday.

"So I fixed the ligament with blood spinning PRP, which is plasmar rich Platelets.

"It took a long time but it worked and I fixed the arthritis with some anti-inflammatories.

"It took six months to get that part right but it took six months to get diagnosed correctly."

The 46-year-old admitted he ventured to some dark places during his near 18-month layoff.

"Not to play golf for a living again has certainly crossed my mind on more than one occasion and I didn't enjoy that," Chalmers said.

"I played here last year just to see how I was going to go and it wasn't any good and I was still in pain.

"My last meaningful event in the United States was July 2018 so my goal is just to get the first one in the air and be pain-free for the duration.

"I've been practising hard here this week and waking up feeling good. So that's a victory already. And if I happen to play great, great. That's awesome.

"But ultimately it's just about competing this week as best I can."

Champion at Royal Adelaide in 1998 before lifting the Stonehaven Cup a second time in 2010 at The Lakes, Chalmers is attempting to join Jack Nicklaus, Peter Thomson and Greg Norman in a rare group to have won the Open at least three times.

But deep down he's unsure how he'll fare.

"You won't know till the gun goes off but I'm hitting the ball nicely in practice. I've just got to play under pressure a little. I haven't done that for a long time so it's going to be interesting," he said.

"But the good news is I'm excited about playing again."

Australian Associated Press