A ring of boos rained down the Emirates at the final whistle to a scoreline even the bookies didn’t predict. On a night when Arsene Wenger renewed hostilities against his former club where he made his mark as manager, the French club ran riot on English soil to take their solid advantage for their home leg at the Stade Louis.
The Gunners lacked the intensity and mentality to cope unlike their disciplined performance against Crystal Palace at Selhurst Park on Saturday. With their lately typical formation 4-2-3-1, there were no changes in the starting lineup from their last time out. Welbeck, Sanchez and Ozil played behind Giroud forming the trio of attacking midfielders and Cazorla played the deep midfield role along with Francis Coquelin.
AS Monaco started with a well-structured 4-5-1 formation, with Dimitar Berbatov relishing his visit back to England and Joao Moutinho’s prolific role in central midfield. Dirar and Martial, the wide midfielders covered the wide zones thus narrowing down the play into the four channels that form the midfield area (Considering the width of the pitch is 90 metres, there are four channels and two wide zones, 15m each)
Leaving wide gaps in Midfield
The Gunners lacked clear intensity while going forward and defending. Giroud missed clear cut openings that could have clearly raised Arsenal stakes for the away leg. Arsenal didn’t play the pressing game too well either as they created wide gaps in midfield. The first goal lead to the space provided between the midfielder in the channel and the wide zone. The space between Cazorla and the wing back popularly known as the half space or Half-braum in German led to Geoffrey Kondogbia running into the area to pull the trigger. 
The play was initially dragged wide by bringing Arsenal defensive midfielders into the wide area thus leaving a wide gap in midfield with Ozil and Sanchez failing to track back. The shot took a slight deflection and hit the back of the net with Ospina undone by the change in trajectory of the ball.
The second goal led to a counter attack when the Martial ran down the wing while Arsenal defenders closed down Fabinho who did brilliantly to shake off Sanchez and put him through. Per Mertesacker also commits himself letting the opposition wide midfielder to run behind him.
As one can see, the black line shows the PASSING LANE which puts Martial through towards the wing. He squared the ball towards Berbatov, who finished it off perfectly. The blue line indicates the movement of Arsenal players while pressing Fabinho thus providing that extra space at the back. During another attack, Arsenal midfielders failed to fulfill their defensive responsibilities, as one can see in the image below. All though the shot was eventually saved, Moutinho was allowed to run into space to provide a cheeky back heel to Martial who sprang his shot towards Ospina.
Oxlade-Chamberlain’s goal was one defining moment that Arsenal could take out of the game, but his defensive frailties lead to Monaco’s third goal. After losing the ball in midfield, he failed to track the run of Yannick Ferreira Carrasco who came on the 75th minute to score the last of the three goals.
The image shows the dash of Carrasco into space, while Silva the substitute who came on Martial put him through towards goal leaving only Per Mertesacker as the last line of defence. The Gunners formidable 4-2-3-1 formation that led to their recent run of form of winning sixteen out of their last nineteen games failed to stand tall. Arsenal looked rusty, tired and clearly lacked intensity to match their French opposition. They have left themselves with a mountain to climb in the second leg along with a gruelling set of Premier League fixtures in March.
Analysis credit: Vignesh Jayanth