Celtic moved eight points clear at the top of the Scottish Premiership after breaking down 10-man Ross County.
The hosts lost James Brown to a 10th-minute red card when an ugly, mistimed tackle was reassessed via the monitor.
County retreated into a defensive shell, frustrating the champions until David Turnbull powered in a shot in first-half stoppage time.
The one-way traffic continued, with Luis Palma adding a stunning strike and setting up a James Forrest header.
A tenth consecutive win for Celtic over County in all competitions was never in doubt after such an early sending off.
The home side, who are now winless in seven league outings, played with commendable spirit but could not get up the pitch to pose any kind of threat.
The early exchanges were played in a shroud of mist, with Jordan White nodding wide for the hosts and Liam Scales prodding the ball home only for Oh Hyeon-gyu to be penalised for the preceding aerial joust.
David Munro had a good view when Brown lunged into a late challenge on Yang Hyun-Jun, catching the winger above the ankle, but the referee was encouraged to review his yellow card decision and a quick look at the replays resulted in a change of colour.