One of the Gunners’ tormentors in chief was former Tottenham striker Dimitar Berbatov, who scored one of the visiting side’s goals and played a key role in the French outfit’s win.
The Bulgarian forward has been vocal in the aftermath of the game and stated that the result was not a shock.
He was also quick to point out Arsenal’s biggest weakness - that they are susceptible to counter-attacks due to throwing too many men forward.
"To be honest, we were not surprised," Berbatov told reporters, published in ESPN.
"Arsenal have very quick players and when they go forward they leave a lot of space at the back.
"We knew that and we had prepared well and took advantage of it. We knew their weaknesses and we exploited them and I think everyone can agree that we deserved our win.
"Our team is very young but very talented. It is not only about age but about class. If you prepare well and do what your coach says, you can see the result. We believed we could do something. This is for everybody."
The Gunners now need a minor miracle when they travel to the Stade Louis II next month - a ground that Arsene Wenger knows well due to his role as the side’s head coach before joining Arsenal.
Arsenal will look to put their disappointing result against Leonardo Jardim’s men behind them this weekend, as they face Everton on Sunday in the Premier League.
Monaco, meanwhile, have a tough clash against title-chasing Paris Saint-Germain on Sunday also.