Ross did fear as many as five first-team members would be in danger of missing this weekend's clash but saw three of his casualty concerns return to training on Friday.
The unnamed player who missed last week's win over Hamilton after contracting Covid-19 will not rejoin Ross' squad until next week after experiencing symptoms which required further checks.
Motherwell captain Declan Gallagher is back in training following a hamstring injury but will not be risked in Edinburgh.
Steven Lawless returned to the bench in midweek but Graham Alexander still has 12 first-team players missing.
Mark O'Hara, Liam Grimshaw (both illness), Bevis Mugabi (shoulder) and Sherwin Seedorf (knee) are sidelined along with recent signings Eddie Nolan, Sam Foley and Harry Smith (all unspecified injuries), plus long-term absentees Trevor Carson, Charles Dunne, Liam Donnelly and Scott Fox (all knee).