Local skirmishes can be a matter of pride, not merely in your own team, but in a treasured, long-standing enmity. If it goes against the grain for football supporters to revel in their rivals, the encounter and the occasion can compensate.
If every derby has its own, distinct claim to be the fiercest, the Black Country meetings of West Bromwich Albion and Wolverhampton Wanderers also appear among the most significant. This is not merely one of the oldest rivalries - their competitive games predate the foundation of the Football League, with Albion winning an FA Cup tie 125 years ago - but one of the closest. The ever-shifting balance of power in their corner of the West Midlands has entailed quests for promotion and battles against relegation over the last decade. Derbies have been pivotal.
It is why, when Wolves and West Brom reconvene this afternoon, much more than a rich rivalry is at stake.
Consider their recent history.
When they last met at The Hawthorns, in February, it was Roy Hodgson's first game as Albion manager. Trailing for 51 minutes, West Brom rescued a point with Carlos Vela's injury-time equaliser. It was the turning point in West Brom's season, the start of a six-game run that brought 12 points and carried them out of the relegation zone and in to the top half of the table.
And yet, if anything, the rematch was even more significant. With three games remaining, Wolves began it in 19th place. Steven Fletcher scored two goals in a Wolves triumph, the first of back-to-back victories that secured their Premier League status.
"Last season was the critical one for them and they survived by the skin of their teeth," Hodgson said. "Strangely, we looked like surviving by the skin of our teeth but didn't have that worry in the end."
But a place in the top flight has been the perennial backdrop when yo-yoing clubs meet. West Brom won at Molineux in April 2008 to go top of the Championship with just three weeks of the season remaining and duly went up; 12 months earlier, Wolves' hopes of promotion were ended by their neighbours when Albion beat them home and away in a play-off semi-final.
The most dramatic turnaround of all, however, occurred in the 2001/02 season when big-spending Wolves, who had been 11 points clear of West Brom with eight games remaining, were overhauled by an unheralded Albion side who confounded expectations by clinching automatic promotion.
So an early-season game takes on a greater importance than simply the stereotypical relegation six-pointer which Albion's start - five points from seven games - and Wolves' form, consisting of four straight defeats, could indicate.
These two are proof that geographical proximity is not the only factor in a rivalry. The Hawthorns is closer to both Aston Villa and Birmingham City than Molineux, but in the Black Country few need question which is the must-win game of the campaign.
Form, as well as history, gives it that status. After early excellence, when they ranked among the league leaders, Wolves have encountered difficulties; their last point came in August.
"We don't want five losses on the bounce; we'll be in dire straits if we lose again," said their captain, Roger Johnson. "We're looking to stop the rot, and even if we don't perform well we must get something out of the game."
West Brom have a similar need. "I think a derby is a good fixture when you're struggling for form," Hodgson said. "Derby matches are always difficult, whether you go into them in particularly good or bad form." Albion's recent record is nothing to brag about but, on their own turf, against their rivals, it is enviable.
Wolves, who will be without the injured Fletcher on Sunday, have not won at The Hawthorns since 1996. Victory would be one to savour because, as the past shows, entire seasons can swing on such days.