The Saints have confirmed Wood will need surgery on his collarbone and expect him to be sidelined for some six weeks.
They are also awaiting tests on speedy forward Liam Henry, who was forced off with hamstring tightness.
Wood was stretchered off and taken to hospital early in Thursday night's 15-point win over the premiers, after colliding with teammate Zaine Cordy and landing heavily when the pair flew for a mark.
Play was held up for several minutes before medical personnel could take Wood off the field.
"He's such a good lad. It was pretty courageous," coach Ross Lyon said post-match.
"He knocked himself out and broke a collarbone. We're concerned about him."
On Friday, the Saints expressed relief Wood was not hurt more severely in the nasty collision.
"Obviously you'd prefer your players not get injured at all, but considering the angle and way Mason landed, we could've been dealing with something far more serious," football boss David Misson said in a statement.
Wood was taken to hospital early on in St Kilda's defeat of Collingwood. (Morgan Hancock/AAP PHOTOS)
Henry, one of the Saints' best players on Thursday night, left the field in the last quarter and did not return.
Misson said the severity of the problem remained unclear.
"We took Liam out of the game towards the end as a precaution," Misson said.
"We'll provide a further update once we have those results back."
Lyon said the Saints learned their lessons well from last week's narrow loss to Geelong.
"It was a step forward. We have plenty of work to do, but confidence comes from action and we delivered the right actions," he said.
"We were pretty relentless from start to finish."
Lyon was delighted with St Kilda's work against 'signatures' in the reigning premiers' play. (Morgan Hancock/AAP PHOTOS)
Lyon praised their young players, such as speedy defender Nasiah Wanganeen-Milera, and said the club's future looked bright.
As Collingwood slumped to an 0-3 start, Lyon said it was becoming more clear what needed to be done to stop the Magpies.
"If you're the reigning premier, you have clear signatures that the opposition need to deal with," he said.
"The competition has maybe taken a while, but we're seeing all those signatures. It's pretty clear. Often it's hard to stop, but we did a pretty good job of that."
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