Simpson hung up the boots at the end of last season following 342 games for Carlton over 18 seasons.

But the 36-year-old is already getting itchy feet, and has announced that he would be willing to join an AFL club via the mid-season draft if anyone wants him.

Simpson says he's been "flogging" himself on the fitness front and would be able to slot back into an AFL environment.

Riewoldt, who retired at the end of 2017 at 34 years of age, said Simpson's plan could potentially be successful.

"Could he do it? I mean if he's done the work ... then there's no reason why not," Riewoldt said on Monday.

"What he would provide is leadership and a real understanding of the game. He's always been a good reader of it. Those are things that never leave you.

"It would be the physical question mark. But only he knows if he's done the work. He's brave putting it out there, good on him."

Riewoldt was thrilled to see St Kilda's comeback against West Coast on Saturday, with the Saints booting the last eight goals of the match to seal the 20-point win.

It came just one week after the Saints copped a shock 75-point flogging at the hands of Essendon.

Riewoldt, who played 336 games for St Kilda, says he never lost faith in the Saints despite the big loss to the Bombers.

"I've been involved in football clubs long enough to know that sometimes we get a little bit too fixated on results, and they tend to dictate too much," Riewoldt said.

Thursday night's clash between St Kilda and Richmond is the latest edition of Maddie's Match, which raises awareness and funds in the hope to find a cure for Bone Marrow Failure Syndromes.

A new fundraising initiative for this year is the Ride for Maddie, which will be held on the morning of the match.

Nick Riewoldt's sister Maddie died in 2015 at the age of 26, and the foundation has become a big part of his life.

"Six years ago when we started this journey, it was really under resourced and an issue that not many people had much awareness about, us included as a family going through it," Riewoldt said.

"We feel like we've been able to take some strides and make some really significant gains in that area."

Australian Associated Press