Nick Riewoldt and his wife Catherine have flown back to Melbourne this morning after the skipper remained at the Royal Adelaide Hospital overnight for observation.

Riewoldt is in good spirits and is expected to return to Linen House Centre on Monday but is unlikely to be available for selection next week.

"I was with Nick this morning at the Royal Adelaide Hospital and he's in good spirits," GM of Football Performance Jamie Cox told Melbourne radio on Sunday.

"He's memory is pretty decent considering what's happened.  He's about as good as you could possibly imagine.  He's got a little mouse under his eye - a bit of a reminder from where they collided but he's going well."

Scans on Saturday cleared the forward of any structural damage after he was concussed 26 minutes into the first quarter of St Kilda's round seven game against the Crows.

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"Fortunately all those results have come back positive so it's all good news at this stage," Cox said.

"We'll go through the usual procedures (for concussion testing) but he is in significant doubt for the weekend."

This is the first time this season Riewoldt has been concussed after suffering whiplash in round one following a collision with GWS's Tom Bugg.

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The club will provide an update on his condition on Tuesday when the weekly injury list is updated.

Jack Lonie also appears to have not suffered any serious damage after also receiving a knock to the head.