Former Celtic striker Scott McDonald was forced to correct himself during an interview after initially referring to Sunday's clash at Ibrox as the "Old Firm".
The Australian played for Celtic between 2007 and 2010 where he won a Premiership title and a League Cup.
And after initially referring to the fixture as the "Old Firm" when talking about the match-up between the fierce rivals in January, he quickly followed up by saying the "Glasgow Derby".
