The Canadian full-back made his first appearance for the club since early August, when he was forced off during Celtic's meeting with Kilmarnock.

Johnston's return to first-team action was marked by his substitution for Colby Donovan at Easter Road, but his involvement was again cut short as he was withdrawn later in the match.

This substitution raises questions about Johnston's fitness, especially as he had only recently returned from the injury that had kept him out of action.

It is currently unclear whether the decision to substitute him was precautionary or if Johnston has suffered a further setback.

Cameron Carter-Vickers was brought on to replace Johnston, indicating another change in defence for Celtic during the match.

Johnston's return was a positive development for Celtic, with the full-back looking to regain fitness and match sharpness following his absence.

However, his latest substitution means his availability for the club's upcoming fixtures could be a point of concern.

Celtic will hope to clarify the situation as more details emerge following the match.