After a poor start to the second half, the Gunners got their gift on 68 minutes when the Frenchman caught Hector Bellerin's heels to give away a penalty.
And Pierre-Emerick Aubameyang slotted into the bottom-right corner for his first goal since mid-October.
But there were several moments on and off the pitch that you may have missed – and Daily Star Sport have picked them out here!
1 Training kit throwbacks
Previous encounters between these Premier League sides can certainly be described as "colourful", from Roy Keane's tunnel clash to that Ruud van Nistelrooy penalty.
But the most colourful event at Old Trafford was the warm-ups, with both sides wearing warm up kits designed by Pharrell Williams in partnership with Adidas for their "Human Race" range.
United's shirt, with the logo appearing to be drawn with large crayon, is a call back to the 1990-1992 away strip with a "tie-dye" blue effect.
While Arsenal fans will remember players such as Paul Merson and Alan Smith wearing the "banana skin" throwback kit between 1991 and 1993.
Maybe a hope from both sides that the kit would bring good fortune?
2 Gary Neville man crush on Arteta
The players were not the only ones drawing attention for their clothing choices at Old Trafford.
Arteta, who made it 25 wins in 40 games as Gunners boss at Old Trafford, was dressed for the occasion.
The Spaniard chose a black overcoat to match his slick hair – and it all proved too much for Neville on commentary duty.
“He always looks a millions dollars - how does he look like that," the former United defender said to a laugh from Martin Tyler.
It brings a whole new meaning to "power dressing"!
3 Rio vs RVP - an old rivalry renewed
This fixture has a history of one-on-one battles such as Keane vs Vieira.
But Rio Ferdinand, who spent 12 seasons facing Arsenal at United, sent a cheeky dig to former Gunners captain and United team-mate Robin van Persie.
Posting a video on Twitter, the former defender asked for a prediction while saying: "I used to love this fixture - Vieira, Henry, Pires – who was the other one? van Persie!"
But the Dutchman, who helped United win their last title when he moved from Arsenal, had his own response.
You never lose that sense of rivalry, even in retirement!
4 Pogba on the precipice?
It was the Frenchman's error that saw Arsenal get the win, catching Bellerin's heels to give away the penalty.
He had already been sent a warning by Roy Keane who had suggested a big performance was needed to show his worth to Solskjaer.
Pogba's error saw him trend on Twitter, with the United faithful dubbing him "criminally overrated".
Having conceded the penalty in the 6-1 defeat to Tottenham last month, the midfielder is living life on the edge.
5 Thomas getting the Partey started
Arsenal's deadline-day move for the Ghanian is starting to look like one of the best pieces of business all summer.
Forming a wall with Mohamed Elneny in midfield, Partey secured the most passes  and the most ball recoveries  in the first half to keep the gate shut to United.
Firing in a fierce shot at David de Gea on 58 minutes, he was also part of the north London side's attacking impetus.
Another stellar performance that is seeing him become a lynchpin for Arteta.