When Manchester City and Manchester United contest the 2023 FA Cup final on Saturday, it will be the first time the two have directly faced each other for a major trophy in their long history.
But while they may not have duelled for silverware until now, the two clubs have rarely been out of each others' eyeline in their 131 years together in England's professional league system.
From their humble Victorian origins to modern multi-billion pound behemoths, a rivalry has emerged and evolved - not always fierce, rarely even, but always important to those who drape themselves in blue or red.
And when the two do clash, sparks fly.
Before Saturday's unprecedented encounter, BBC Sport presents a journey through the clubs' shared history, looking at their respective highs, lows and all the most significant meetings, from Ardwick v Newton Heath to "Agueroooooo" and beyond.