 Complete the following phrase:  Celtic and Rangers are the two biggest teams in Scotland, and the Old Firm rivalry is one of the most heated football rivalries in the world. The Old Firm rivalry is largely motivated by religious sectarianism, and is related to the conflict between Loyalists and Republicans in Northern Ireland. Rangers hooligan element the ICF have a strong rivalry with Celtics CSC and Aberdeens ASC, with Celtic being their traditional cultural enemy. They have also had major clashes with Motherwell, Hibs, Partick Thistle and Dundees Utility. At the 