It's been said that the sheer emotion of the Old Firm derby between Scottish soccer giants Rangers and Celtic only can be fully understood by those born and raised in the city of Glasgow.
So much more than just a sporting rivalry, the ancient animosity between Scotland's two biggest clubs manifests itself in feverish fashion in the weeks leading up to any match between them.
Historical undercurrents of division along political, religious and sectarian lines make an Old Firm clash a tinderbox ready to ignite at any time – be it on the field, in the stands or in the city itself.
That is the situation DaMarcus Beasley of Fort Wayne, Ind., finds himself in this week.
Beasley, who signed with Rangers from Dutch club PSV Eindhoven during the offseason after spending the previous campaign on loan at Manchester City, is gearing up for his first Old Firm game. Nothing he has experienced in his career so far can prepare him fully for the experience, but just living in Glasgow for the past four months has given him a taste of the level of feeling the matches inspire.
For all of Beasley's impressive performances in the Scottish Premier League, plus an outstanding display in Rangers' Champions League victory over French champions Lyon, this is the one that really counts.
"It didn't take long to understand the passion when I arrived," said Beasley, who spent four years with the Chicago Fire before beginning his European adventure in Holland.
"It pretty much takes over the whole city. Everything and everyone is either Rangers or Celtic. It is something you don't really see in America, and I find it amazing."
The Scottish league often is derided for lacking the quality of bigger European leagues, and even its most loyal followers would admit that outside of Rangers and Celtic – who have won every title between them for the past 22 seasons – there is a sharp dip in quality.
However, those players who stand tall and reserve their finest for the matches that determine months' worth of bragging rights, never can have their character and fortitude called into question.
The atmosphere that surrounds this rivalry always is oppressive, occasionally ugly – but permanently fascinating. It must be seen to be believed. For those whose loyalty to their club is determined at birth, it is everything.
That's why expectations take on a whole new meaning for an Old Firm player. Winning the league – and winning the derbies – is the standard requirement at the end of any given season.
"It is a different kind of challenge," Beasley said. "It is a new chapter in my career, and it is very exciting. There is that level of pressure when you are at a club like this, and it is up to me to respond to it."
Historically, Celtic has been a primarily Catholic club, with Rangers followers mainly Protestant in faith. Those leanings also have extended to politics pertaining to the situation in Northern Ireland, which is split between Loyalist and Republican views.
There have been moves by both clubs in recent years to separate the sectarianism from the sport, but such feelings never can be completely quelled merely by being pushed beneath the surface.
Few players have played for both clubs. One who did, current Toronto FC coach Mo Johnston, faced regular taunts of "Judas" when he signed for Rangers in 1989, two years after leaving Celtic. This weekend's game is crucial as is typical, with Rangers three points behind league-leading Celtic and keen to plug the gap at the top.
Beasley exchanged some good-natured banter with the Celtic fans he encountered around Glasgow, but he has noticed a change in atmosphere as Saturday's big game draws closer.
"You see even in preseason, when the crowds we had were ridiculously big, what the sport means to the people here," Beasley said. "I get noticed by the Celtic fans, but it hasn't been too bad.
"It could be a bit different if I score the winner in the Old Firm game, though."