Scott McKenna missed Scotland's last training session before their World Cup clash against Morocco on Friday night.
The 29-year-old Dinamo Zagreb centre-back was absent for the 1-0 Group C win over Haiti on Saturday with a calf injury, before returning to Steve Clarke's group at the Atrium Health Performance Park on Tuesday morning.
However, McKenna sat out Wednesday morning's workout before the squad's afternoon flight to Boston.
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Scotland, looking to qualify to the knockout stages for the first time, are top of pool with three points, after Morocco and Brazil drew 1-1 in their opener in New Jersey.
After taking on Morocco, Scotland -- competing at the World Cup for the first time since 1998 -- face a final group fixture against the Brazilians on June 24.
