We take a look at the memorable clashes between these two giants of English football as they collide yet again at Old Trafford on Wednesday.
There is no doubt that there has been a shift in the success pendulum between these two this season.
Manchester United finished second last season, while Arsenal failed to make the top four, coming up in sixth. However since Unai Emery has taken charge of Arsenal things have changed.
The London club are currently enjoying a 12-match unbeaten run, occupying fourth in the Premier League table and sitting eight points above Wednesday night's opponents, in the process.
Mourinho's men are without a win in three, sharing the spoils in their last two fixtures against Crystal Palace and Southampton respectively, which has left United in seventh.
With Mourinho under pressure and Emery keen to keep the gap with the leaders as close as possible, there is plenty to play for on Wednesday night.
So let's delve into the recent history of Manchester United versus Arsenal and pick out five famous affairs between the two.
Manchester United 0-1 Arsenal (May 2002)
- This was an enjoyable match for the travelling Arsenal fans, which will last long in the memory as their side sealed the double with this victory at Old Trafford, clinching the title to add to their FA Cup glory.
- Without Thierry Henry, Arsenal still asserted their dominance over their title-challengers, but ultimately only one goal separated the two sides.
- This came from Sylvain Wiltord, who calmly slotted the ball past Fabien Barthez after he initially saved Freddy Ljungberg's effort.
Manchester United 0-0 Arsenal (September 2003)
- This tasty fixture was later crowned the 'Battle of Old Trafford' as there was just about everything involved, except from goals.
- The end result was significant as Arsenal went on to finish the season unbeaten, labelling them as the 'Invincibles', although this was very nearly not the case.
- Patrick Vieira was sent off in a match that witnessed eight bookings, including two for himself, as well as a penalty decision go the way of Ruud Van Nistelrooy and Manchester United.
- The United frontman proceeded to thump his penalty off the bar, and chaos ensued. Martin Keown confronted the striker and jumped up, bringing his arms down on Van Nistelrooy in doing so, while Lauren and Ashley Cole supported the Arsenal centre-back in the attack.
- Five Arsenal players and two United players were forced to pay fines as punishment for their part in this battle.
Manchester United 2-0 Arsenal (October 2004)
- This contest was given the name, 'Battle of the Buffet' as a melee followed the final whistle in the tunnel.
- One of the issues stemmed from a tackle by Ruud Van Nistelrooy, again, on Ashley Cole in the 19th minute, which he was then banned for later as referee Mike Riley did not deal with it accordingly in-play.
- This proved to be pivotal as the Dutchman later converted a penalty in their 2-0 victory, which subsequently ended Arsenal's 49-match unbeaten streak.
- Arsenal's frustration spilled into the tunnel as the whistle blew, with Cesc Fabregas throwing pizza at Sir Alex Ferguson in the midst of the confrontation, only later confirming he was the culprit in 2017.
- Arsene Wenger was not happy with Van Nistelrooy and branded him a 'cheat', which he was later punished for, having to pay £15,000 due to his post-match comments.
Manchester United 2-1 Arsenal (August 2009)
- Arsene Wenger was in the thick of it once more, as he was sent to the stands after kicking a water bottle in frustration, when Robin Van Persie's late strike was ruled out for offside.
- His Arsenal side squandered a one-goal lead as United came from behind to get the victory, as Abou Diaby's own-goal was the difference..
- Andrey Arshavin had put Arsenal ahead, before Wayne Rooney levelled with a penalty and Diaby heaped the misery on Wenger and the Gunners fans.
- Arsenal seemed to have a clear penalty ruled out when Darren Fletcher handled in the box, as well as Van Persie striking one off the bar before his disallowed goal, proving a testing afternoon for the man in the Arsenal hot seat.
Manchester United 8-2 Arsenal (August 2011)
- This is one of the most enjoyable days in the recent memory of the Old Trafford supporters, as they inflicted Arsenal's worst defeat since 1896.
- Park-Ji Sung, Nani and Danny Welbeck were among the scorers in the romp, with Ashley Young also claiming a brace in the emphatic, brutal victory.
- Wayne Rooney stole the headlines as he netted his sixth Manchester United hat-trick to see off an Arsenal side depleted by injuries and suspensions.
Returning to the present, Arsenal will move 11 points clear of Manchester United with victory at Old Trafford, while the Red Devils could rejuvenate their form and a top-four charge with a win against Emery's Arsenal.
Watch the contest live on Sky Sports, from 1900 GMT on Wednesday.