ST KILDA are set to rest in-form Justin Koschitzke for their NAB Cup semi-final despite spearhead Fraser Gehrig picking up an injury which will sideline him until the start of the home and away season.

Scan results on Monday will determine the extent of a calf injury to Gehrig, who broke down during the second quarter of the Saints' five-point NAB Cup win over Geelong in Canberra on Saturday.

The club confirmed on Sunday Gehrig had a suspected calf strain which was likely to keep him out for at least three weeks - a time frame which would make him touch-and-go for the round one-clash in the Toyota AFL Premiership with Sydney on March 22.

"It won't affect him you wouldn't think for round one," Saints coach Ross Lyon said after Saturday's match.

Koschitzke, who kicked five goals against the 2007 premiers in a stunning performance in Gehrig's absence, is scheduled to be rested next week as part of the club's pre-season rotational policy.

The absence of two of their star forwards could tempt the Saints to unleash skipper Nick Riewoldt for his first match of the season in Friday night's NAB Cup semi-final against Essendon at Telstra Dome.

It would put to rest rumours which persisted throughout last week that Riewoldt had a serious knee injury. The Saints released video footage of Riewoldt on the club website late last week of the star forward training unhindered at Moorabbin that day.

The club also said midfielders Lenny Hayes and Luke Ball were slated to return against the Bombers, who gave the Western Bulldogs a 54-point whipping at Telstra Dome in their quarter-final to set up a showdown with the Saints.

Lyon said having their next match in Melbourne was ideal for his side, rather than a trip to the Gold Coast which would have been their fate had they lost to Geelong in Canberra.

"It means we're through to the third week and we can build for round one a little bit more and we don't fly, so that's a win, because I think we would have been off to the Gold Coast," Lyon said.

"We were exposing our list and our younger players stood up again. We got a little bit of luck and you move on to the semi-final."

Collingwood are expected to find out on Monday that young forward Brad Dick faces a knee reconstruction after his injury in the 33-point practice match loss to West Coast in Western Australia on Saturday.