St Kilda ended the game with just one fit player on the bench, and Tom Simpkin battling on after receiving a knock, as it went down to Geelong by 101 points.
Alongside the injured Riewoldt sat key defender James Gwilt – who was subbed out of the game during the second quarter with a knee injury – and Lenny Hayes, who hurt his hamstring.
St Kilda coach Scott Watters said all three players were unlikely to play next week against the Brisbane Lions.
He said Gwilt had suspected bone bruising on the knee – the same one that was reconstructed in 2011 – but little would be known for certain until his knee was scanned.
After hurting his foot in the third quarter, Riewoldt tried to keep going but it was clear he was unable to run. He could not chase and Geelong's defenders exploited his lack of mobility on the rebound.
"We tried to just – not hide him in the goalsquare, which is almost impossible today – but with the risk factor involved it was time to put him to sleep today," Watters said.
It would have been interesting to see what would have happened if the champion had literally stood in the goalsquare.
Given the Saints had just 26 inside-50s and did not kick a goal in the second half, it may not have made too much difference. Riewoldt had battled hard for his two goals up until half-time.
It was just Hayes 10th game for the season and the news as to the severity of his hamstring injury will be sweated upon. The 33-year-old champion remains as tough as ever and his absence would be a blow for the Saints.
Watters said the team had no excuses. Geelong is a tough assignment at the best of times and the Saints suffered a similar fate to most.
It could not move the ball from deep into defence beyond the middle of the ground as Geelong just won contest after contest forward of centre.
Anytime St Kilda got it past centre Harry Taylor, Corey Enright and Andrew Mackie just sat back and won the ball.
Watters said Sam Dunell and Sebastian Ross were chances to return to the team if they played well in the VFL on Sunday.
Anytime St Kilda got it past centre Harry Taylor, Corey Enright and Andrew Mackie just sat back and won the ball.
Watters said Sam Dunell and Sebastian Ross were chances to return to the team if they played well in the VFL on Sunday.
Rhys Stanley battled hard in defence and Watters admitted in an ideal world, he would play forward.
He praised Jack Steven – who was good again even though he turned the ball over occasionally – and said he would like to think the 23-year-old was having a good enough season to be in All Australian contention.
Steven had 36 disposals, but the Saints had nine players who had fewer than 10 possessions leaving too much to too few.
"This is tough to swallow this type of result, but ultimately to survive in this type of competition you have got to take that.
“But that has got to drive your training, drive your preseason and drive your improvement as a club," Watters said.
He praised Jack Steven – who was good again even though he turned the ball over occasionally – and said he would like to think the 23-year-old was having a good enough season to be in All Australian contention.
Steven had 36 disposals, but the Saints had nine players who had fewer than 10 possessions leaving too much to too few.
"This is tough to swallow this type of result, but ultimately to survive in this type of competition you have got to take that.
“But that has got to drive your training, drive your preseason and drive your improvement as a club," Watters said.
