There are many great derbies in world football, but few succeed in ticking all the boxes as emphatically as Glasgow's 'Old Firm'. This is a match with a history like no other, rooted in - and fashioned by - a long and passionate mutual enmity that extends far beyond the sporting arena.
The result is that, around the world, even those who know little about Celtic or Rangers tend to have heard tales of the feuds and fireworks that erupt when Glasgow's two tribes go to war.
"A friendly encounter." That, ironically, was how the first-ever Old Firm derby was described in the local press when Rangers accepted an invitation to contest Celtic's inaugural match on 28 May 1888. Such cordiality would, of course, prove short-lived.
As the rivalry grew, so did the dominance of the clubs themselves. So large did their crowds and coffers swell, in fact, that a popular periodical at the time, The Scottish Referee, made a sneering reference in April 1904 to the profiteering of "The Old Firm of Rangers, Celtic Ltd". Needless to say, the term stuck.
Early relations may have been convivial, but the clubs' respective philosophies made conflict all but inevitable. When Celtic was founded in November 1887 by an Irish Catholic monk, its sole stated objective was to fund a charity aimed at alleviating poverty within Glasgow's large Irish community. It was, however, also hoped that this club would provide a symbol of pride around which these downtrodden immigrants could rally. Rangers, by contrast, were the establishment team of Scotland's Protestant majority and, until a famous 1989 watershed, followed a notorious policy of refusing to sign Catholics.
Facts and figures
Aside from the social and political factors that make this fixture so unique, no other local derby is fought out by two such dominant forces in their national arena. Celtic and Rangers boast a staggering combined tally of 172 league championships and Scottish Cups, and their Premier League duopoly stretches back 31 years.
Rangers have retained a narrow statistical edge in the derby itself, with 159 wins to their rivals' 145, while an early Ibrox legend, Robert Hamilton, remains the fixture's all-time top scorer with 35 goals. The clubs also hold the British record attendance for a league match - 118,567 at Ibrox on 2 January 1939 - and an even bigger crowd, 132,870, turned out to watch them contest the 1969 Scottish Cup Final.
Tales of derbies past
In winning 5-2 against a club 16 years their senior in that first-ever meeting 121 years ago, Celtic established a tradition of unpredictability in the Old Firm that has endured ever since. Regardless of the clubs' fortunes and form, forecasting the result of a Glasgow derby is notoriously tricky, with the 1957 League Cup final a prime example.
Rangers, who went into the match on the back of a second successive league title, arrived at Hampden heavily tipped to make light work of a struggling Celtic side. Instead, Scotland witnessed what The Sunday Post described as "an October Revolution", as the Bhoys won 7-1, racking up a British record scoreline for a domestic cup final that stands to this day.
In the blue half of the city, Rangers fans still revel in the memory of their 100th league victory over their old rivals: a 3-0 win at Celtic Park in 1999 that secured the title and sparked violent scenes on and off the park. Certainly, for all its passion, much about the Old Firm's history is distasteful and, like any great drama, the fixture has had its share of catastrophes.
In 1931, an iconic and tragic figure emerged in the shape of Celtic's John Thomson, a brilliant young goalkeeper who suffered fatal head injuries in diving bravely at the feet of a Rangers striker. Worse was to follow 40 years later when 66 Rangers fans died in what would become known as 'the Ibrox disaster' after barriers gave way as supporters were leaving the stadium.
Jock Stein, the legendary Celtic manager of that era, returned from the dressing room to offer help to those injured and dying, and expressed the hope that it would lead to a new sense of perspective in the city. His plea was that: "This terrible tragedy must help to curb the bigotry and bitterness of Old Firm matches."
The rivalry today
Although it took longer than Stein would have wished, the Old Firm derby did become marginally less toxic as the years passed. In 2008, this manifested itself in an unprecedented and hugely poignant show of unity when Walter Smith and Ally McCoist - Rangers' manager and assistant-manager respectively - helped carry the coffin of a Celtic legend and close friend, Tommy Burns.
However, this old rivalry went on to take a new twist in 2012 when Rangers went into liquidation, leaving the Ibrox club’s supporters to endure the indignity of their team starting again from the bottom tier of Scottish football. Sunday’s Scottish Cup semi-final will, in fact, represent just the second meeting of these sides since the Gers’ financial collapse, and the first since they recently earned promotion back to the top flight.
Yet while Rangers are still rebuilding, and Celtic are themselves widely considered a diminished force, the sides’ current status does not, it seem, serve to weaken the appeal of this fixture. As Henrik Larsson, a veteran of both El Clásico and De Klassieker, said this week: “I never experienced anything, either before or after, that compared to my Old Firm games in Scotland. That was the best atmosphere and those were the most fierce encounters I ever played in.”