NICK RIEWOLDT will test out his injured calf on Thursday in a bid to prove his fitness to play in Sunday's tribute game for his late sister.

Results of scans from late Monday showed a low-level calf strain, suffered during Sunday’s loss to GWS.

St Kilda football manager Jamie Cox said Riewoldt would have to prove his fitness on Thursday. 

"He'll need to do something significant on Thursday, he'll need to be running around," Cox told at Seaford on Tuesday.  

"The game is (on) Sunday, so it gives us a chance to test him out, and then recover again the next day, just to make sure that he's OK.”  

But Cox was reluctant to put a percentage chance on Riewoldt taking the field.

"I won't get too technical, but it was a low-level injury. It's really quite pleasing from that perspective,” he said.

"We just want to give him every possible chance, we want to give him a chance to for the injury to settle - it probably hasn't fully settled yet.”

The St Kilda skipper injured his calf against the Giants on Sunday, but believes he could still be fit to face Richmond.

Riewoldt spoke to reporters as he arrived for scans late on Monday. 

"Obviously (I) want to play every week, but this is a really significant week for obvious reasons," Riewoldt said.

"It is still only early, I'll have the scan and talk to the doctors and go from there basically.

"I think I got it pretty early. I just felt it tighten up a little bit and then came off."

Sunday's twilight encounter between St Kilda and Richmond is being billed as 'Maddie's Match'.

The game is a fundraiser for Maddie Riewoldt’s Vision, which has been set up to raise funds and awareness for research into bone marrow failure syndromes.

Riewoldt's sister Madeleine passed away from a long battle with the illness in February at the age of 26.

St Kilda players took part in a recovery session at the club's Seaford pool on Tuesday morning wearing purple speedos, Maddie's favourite colour, to promote the match.