Premier League sides Arsenal and Manchester United meet for the first time this season at Old Trafford on Monday night.
The two clubs have a history of hostility, with past encounters becoming volatile both on and off the pitch.
Here, PA takes a look at how this grudge match evolved.
Old Trafford brawl leads to points deductions
The 21-man brawl which marred the meeting of the sides on October 20, 1990 had been coming. Arsenal felt aggrieved by the dismissal of David Rocastle during a 1987 meeting of the sides – Sir Alex Ferguson's first encounter with the Gunners – and Manchester United's Brian McClair was goaded by Nigel Winterburn after missing a penalty in a 1988 FA Cup tie. It all boiled over in 1990, as McClair took exception to a Winterburn tackle to spark the melee.
The Football Association took a dim view, deducting Arsenal two points and Manchester United one.
The Gunners overcame that punishment to claim the First Division title.
In your face (part one)
Arsenal defender Martin Keown could not contain his delight when Ruud Van Nistelrooy missed a decisive late spot-kick in a match between the sides in September 2003.
He goaded the Dutchman, screaming in his face and hitting him on the back, having conceded the penalty with a foul on Diego Forlan.
The miss was about as close as the Gunners came to being beaten that season, when they became 'the Invincibles'.
In your face (part two)
The next league meeting of the sides in October 2004 saw Arsenal's 49-match unbeaten run finally come to an end.
On the pitch, it was 2-0 to United but off it, it became known as the 'Battle of the Buffet' after another skirmish in the tunnel included a slice of pizza being thrown at Ferguson.
In 2017 Cesc Fabregas admitted on Sky quiz show 'A League of Their Own' that he was the guilty man.
Fabregas confirmed the pizza hit Ferguson in the face and added: "I apologise Sir Alex, really didn't mean to do that!"
See you out there
Simmering tensions were evident again when the sides met at Highbury in February 2005.
United captain Roy Keane took exception to what he thought was Arsenal counterpart Patrick Vieira trying to intimidate Red Devils defender Gary Neville.
The incensed Irishman had to be calmed down by referee Graham Poll and repeatedly warned Vieira: "We'll see you out there."