NICK Riewoldt will stay in hospital overnight for observation after being cleared of structural damage following a collision during Saturday's match against Adelaide.

MATCH REPORT: Brave Saints fall to Crows

Riewoldt was taken to Adelaide Hospital immediately after the head collision with Brodie Smith in the final minutes of the first quarter.

He underwent CT scans which showed he sustained no serious damage and is now in a stable condition.

"They're looking at him from a concussion point of view, just for observation purposes," coach Alan Richardson said.

"He's up, cracking jokes with a couple of the staff, he's feeling OK but he does need to stay in for the night.

"Riewoldt took 30 more marks than anyone in the competition last year and he is a player that can score goals and connect the defence to the offense and we have struggled without him.

"Our best performances have been with him in the team."

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This is Riewoldt's only concussion this season after he suffered whiplash in round one following a collision with Tom Bugg.

The Saints had a bad day of injuries on Saturday, with Jack Lonie also concussed and handed the red vest. Leigh Montagna (hamstring tightness) and Jarryn Geary (corked quad) were late withdrawals. Both Montagna and Geary are expected to be available for selection next weekend.