Robbie Neilson's sending off was described as a ''pivotal'' moment by his manager as Dundee United subsequently slumped to a 4-0 defeat yesterday.
There was both frustration and disappointment at the actions of the full-back who caught Georgios Samaras with his elbow in a midfield aerial challenge and was shown a straight red card by referee Iain Brines after 28 minutes. United, who had been causing Celtic problems, eventually leaked four goals as Neil Lennon's side strolled into the semi-finals of the William Hill Scottish Cup.
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