ST KILDA has been boosted by the news that forward Nick Riewoldt's right knee injury is not as bad as first thought, with scans confirming no structural damage.

The 34-year-old was a disconsolate figure as he was taken from the ground on a stretcher to a standing ovation late in the final quarter against Melbourne.

Riewoldt took to social media on Sunday morning to confirm the good news, but remained unsure about how many weeks he will miss.

"Thumbs up! Scans revealed no structural damage," Riewoldt posted on Instagram.

"No timeframe for return but prognosis good. (Son) James was excited Daddy got to ride on the buggy.

"Thanks for the well wishes."

St Kilda general manager of football performance Jamie Cox said the prognosis was relatively positive.

"While scans have confirmed there is no structural damage to Nick's knee, the hyperextension of the incident has caused some trauma around the joint and bone bruising which will likely take a few weeks to settle," Cox said.

"We will treat this symptomatically over the next couple of weeks and provide further updates throughout Nick’s rehabilitation."

Riewoldt initially feared he had ruptured his anterior cruciate ligament after hyperextending his knee in the marking contest and hearing a "pop" as he fell to ground.

However the veteran goalkicker was able to walk unassisted in the rooms and was assessed by club medicos for any structural damage, with the initial diagnosis positive.

"The docs are pretty happy the testing that they've done (shows) that it's not an ACL, but there's clearly something in there," a relieved Riewoldt told Fox Footy after the match.

"It's stiff and sore now … I gave it a pretty good wrench.

"It looks like I've dodged a bullet". 

Riewoldt ended the season opener with a game-high four goals to go with his 14 disposals and seven marks.

The 320-gamer handed over the Saints' captaincy to teammate Jarryn Geary this year after 11 seasons in the role.