Ange Postecoglou accomplished what Brendan Rodgers and Martin O'Neill also did with the domestic clean sweep, which was completed last Saturday at Hampden with a 3-1 victory over Inverness CT in the Scottish Cup Final.
But Nicholas prefers the Ange version above the other two based on spending less than O'Neill, who had a Celtic scoring legend at his disposal, and the fact that Rodgers had no Rangers to go head-to-head with given they were still on their "journey" during his tenure.
He wrote in his Daily Express column: "Ange Postecoglou will leave as Celtic's greatest modern-day manager. Some fans might argue that Martin O'Neill or Brendan Rodgers deserves that label, but not me.
