Midfield duo Tony Dingwall and Michael Gardyne return as County look to build on Saturday’s 2-1 victory over Dundee United.
Dingwall was suspended for the Tannadice win, while Gardyne sat out the match under the terms of his loan deal from United.
Midfield trio Rocco Quinn, Ben Frempah and Richard Brittain are all back in training following long-term injuries but are not expected to feature.
The home side, who are hoping to put more distance between themselves and the relegation play-off position, will again be without defender Darren Barr as he recovers from a knee injury.
St Johnstone, who are currently fifth in the standings, will have to assess Murray Davidson ahead of Tuesday’s match.
The midfielder picked up an ankle injury during Saturday’s 1-1 draw at Hamilton.
However, striker Steven MacLean, who sat out that game on the artificial surface at New Douglas Park, following previous knee operations, will be back in contention for a place in the starting XI.