Watch the highlights - I think their scorer is on the line when the ball is prodded forward and is moving back into play when he turns the ball in. Donaldson is our furthest player back and the goalscorer is slightly beyond him - watch Donaldson - he immediately appeals.

Briefly it looks like he came back from an offside position but looks like , is it Donaldson stood on the line ,is playing him onside.

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There has to be 2 players between the attacker and the goal line and Loach is further forward than the scorer and therefore Donaldson is only one player beyond the attacker - therefore he is in an offside position and comes back to turn the ball in.
Offside !