John Hartson in awkward Celtic and Rangers 'Glasgow derby' explainer as he offers fan excuse in on-air exchange

Defiant John Hartson insists he now calls the Old Firm clash with Glasgow derby because "he is Celtic" in an exchange with Craig Moore.

The rivalry in Glasgow is reaching boiling point ahead of Sunday's top of the Premiership clash as Ange Postecoglou's leaders face champions Rangers.

With tensions rising between the two sides, even the name of the derby clash has added fuel to the fire.

Former Celtic striker Scott McDonald started the debate again as he correct himself during an interview after initially referring to the clash as the "Old Firm".

He then switched to calling it the Glasgow derby, which saw an angry caller asking for former Rangers star Craig Moore and Hartson to give their take on the Go Radio Football Show.

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Moore said: "It's Old Firm derby for me all day long. I've always seen it as the Old Firm derby. Everyone has got their own take on it.

"Since coming back (to Scotland) 18 months ago, we've done a bit pre-show and it's the Old Firm. That's the title decider that's coming on Sunday. That's the Old Firm."

However, Hartson disagreed stating: "Well, the last few times (I've been on) I've said Celtic/Rangers.

"I think there's a view that a lot of Celtic fans say now it's the