The 34-year-old has impressed in eight games this season, but missed last week’s 40-point loss to the Western Bulldogs with bone bruising.
Saints coach Alan Richardson denied reports the former skipper has already been ruled out of the Adelaide Oval clash, but agreed his participation was a long shot.
“I didn’t know that it was as emphatic as that, but it’s looking unlikely,” Richardson told Fox Footy’s AFL 360.
“We would have hoped by now that he was able to do a little bit more.
“The last message I had with the docs was that it was unlikely but we’ll give him every chance.”
Richardson warned it would be folly to rule out out the 327-game veteran given his track record of overcoming seemingly impossible odds to take the field.
“He is a bit of a freak that way… not only is he able to get himself up to play but he can play really strong footy,” he said.
“It’s not like he just limps over the line when he does declare himself ready to play.
“But it’s looking more unlikely than likely.”
The match is a pivotal one for St Kilda, who are 10th with five wins and five losses.
Adelaide Oval hasn’t been a happy hunting ground for Riewoldt or the Saints.
In six matches at the venue – three against Adelaide and three against Port Adelaide – St Kilda are yet to register a win, while Riewoldt was hospitalised after a sickening head clash with Crow Brodie Smith in 2015.
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