NICK Riewoldt says he's still "a really big chance" of passing a fitness test on his injured calf and playing in Sunday's tribute match for his late sister. 

But the St Kilda skipper said it would be the club's call whether he is given until the last minute on game day to take his spot for the twilight clash with Richmond at Etihad Stadium.

"At this stage, I'm aiming to train on Thursday and then we'll know more," Riewoldt said on Wednesday morning.

Riewoldt faces Thursday test for Tigers clash

The skipper is battling a low-level calf strain he sustained during last Sunday's loss to Greater Western Sydney.

"The scan was as positive as it could be with that type of injury. At this stage, I'm still a really big chance of getting up (to play Richmond)," he said.

"Clearly, I'll do everything I can and then we'll make the call later in the week."

Riewoldt appeared at Melbourne Zoo on Wednesday with his cousin Jack to promote 'Maddie's Match', which will raise money and awareness for Maddie Riewoldt's Vision and the fight against bone marrow failure.

Maddie passed away from a long battle with the illness in February at the age of 26. 

Riewoldt took compassionate leave from the club and has battled his emotions on match days since Maddie's passing, and the Saints star couldn't be sure how he will respond this Sunday.

"What I do know is I've gone into games this year struggling a little bit emotionally at times, but once I've been out there I've been fine," Riewoldt said.

"The two hours on game day is almost a bit of an outlet to be able to go out and do what you do.

"I think this week will be pretty similar. Obviously the build-up will be pretty big. The reason we're doing it – there's a lot of grief involved – but to be able to do something positive with our grief as a family has been really helpful.

"If we can help other families and other individuals to not go through what Maddie and our extended family have been through, that will be a great result." 

Tigers spearhead Jack Riewoldt hopes his cousin is fit for this weekend, regardless of the lift it will give the Saints.

"It would be fantastic for obviously the Saints for starters, but for the vision and the effort we've put into that, I would love to see him out there," he said. 

Fans attending 'Maddie's Match' are asked to wear a touch of purple, Maddie's favourite colour, and $5 from every adult ticket sold will be donated to MRV.

Exclusive #FightLikeMaddie merchandise will be on sale at the Saints' Locker Outlets on the Etihad Stadium footbridge and inside gates three, five and seven, while match-worn guernseys and purple 'Budgy Smugglers' will be auctioned at