De Gea was rested for the game, with Sergio Romero instead between the sticks.
De Gea has proved to be one of the best goalkeepers in the world during his time at United.
It has seen him being linked with Real Madrid in the past – but the Spaniard is now into his eighth year in England.
De Gea was watching the game as United sought a memorable win at the Emirates.
And the goalkeeper was evidently delighted with how the Red Devils raced into a 2-0 lead.
Alexis Sanchez scored the opener against his former club and De Gea cheekily tweeted an embarrassed face emoji alongside Sanchez’s Twitter handle.
And when Jesse Lingard made it 2-0 De Gea simply tweeted three fire emojis.
Arsenal halved the deficit before half time but United certainly had the upper hand from the first 45 minutes.
And fans were lapping up De Gea’s tweets.
“YES DAVE,” one fan tweeted.
Another wrote: “Hahahahahaha main man David”
A third put: “You are all of us!”
And a fourth tweeted: “I love how this mans just commenting from Manchester”