Sir Alex Ferguson against Arsene Wenger and Roy Keane versus Patrick Vieira - there was battles within battles as these two rivals squared off in literal war for the victory
From titles being decided, to food being thrown in the tunnel, to countless red cards, to continental semi-finals and FA Cup finals - a Gunners and Red Devils match would provide unparalleled entertainment.
But suddenly its significance deteriorated rapidly - starting with Arsenal's decline following their Invincibles season and 2005 FA Cup final triumph - incidentally against United.
The emergence of Chelsea and Manchester City as footballing powers, and United's inevitable fall following Ferguson's retirement also contributed to a reduction in the standing of the Gunners-Red Devils's rivalry.
No longer were Arsenal and Manchester United fighting each other for titles, cups or continental competitions - they were battling to keep themselves among the the big boys and in touch with the top four.
And so the usual fierce contest lost its allure and even though there may have been anticipation before each match between the two old rivals, it has rarely delivered.
But on Monday morning (AEDT), we have an Arsenal - Manchester United match with a result that will have great significance to the top four battle.
The Red Devils have pulled themselves back from the brink of missing Champions League under Jose Mourinho, to be clear in fourth position with nine matches to play thanks to the guidance of Ole Gunnar Solskjaer.
Arsenal are one point behind in fifth position and are undergoing their own revolution under Spanish coach Unai Emery - having impressed in fleeting glimpses in their first season without Arsene Wenger in charge since 1996.
Manchester United are coming off one of their greatest ever comebacks to knock Paris Saint-Germain out of the Champions League despite a two-goal disadvantage from the home leg.
While form may dictate that Solskjaer's men are favourites, injuries to several crucial players including Anthony Martial, Nemanja Matic, Ander Herrera, Jesse Lingard and Juan Mata, means there will have a thread-bare squad in one of their most important matches of the season.
The result of the game won't decide the battle for fourth spot but it will give a huge boost of momentum to a victor and it's nice to have a fixture between these old foes that actually means something again.