Former Celtic manager Ange Postecoglou says he will be watching this Sunday’s derby when the Bhoys visit Ibrox to face Rangers. Postecoglou enjoyed two dominant years in Scotland, including winning a superb domestic treble, before moving to take charge of Tottenham Hotspur last summer. The Australian has never hidden his enjoyment of the Celtic experience and will now get to watch on as a supporter rather than locked in the heat of battle. The Spurs boss will oversee his team’s match at home to Nottingham Forest later on Sunday evening but the early kick-off in Glasgow means he won’t miss a mo…