Match ends, Arsenal 1, Monaco 3.
- Berbatov doubles Monaco lead
- Oxlade-Chamberlain pulls goal back in added time
- Ferreira Carrasco restores two-goal advantage
- Arsenal must score at least three in second leg
- Wenger says Gunners were "suicidal defensively"
Arsenal's hopes of reaching the quarter-finals of the Champions League for the first time since 2010 suffered a stunning blow as they slumped to a shock 3-1 home defeat by Monaco.
The Gunners looked to have been handed a favourable draw but a display that plumbed the depths of incompetence and naivety leaves them facing a last-16 exit once more.
Monaco, resilient at the back and capable of punishing Arsenal's shoddy defence, took the lead in the first half through Geoffrey Kondogbia's deflected shot.
To add insult to injury, former Tottenham striker Dimitar Berbatov added the second just after the break. There was even time for Arsenal to cast away the lifeline substitute Alex Oxlade-Chamberlain's stoppage-time goal had given them as they were caught hopelessly on the counter once more as Yannick Ferreira Carrasco added a third goal.
As Monaco coach Leonardo Jardim did a Jose Mourinho-style celebration sprint down the touchline, Arsenal counterpart Arsene Wenger looked crestfallen and no wonder.
This stage has become Arsenal's perennial stumbling block but Wenger would have had high hopes of clearing the hurdle against his former club, even though they had lost only once in their last 17 games.
But Arsenal were devoid of ideas and when they did create chances they fell to the hapless, and on this night hopeless, Olivier Giroud, who missed every one that came his way.
The eternal optimist Wenger will still believe they can escape from this hazardous position - but they will need to produce something on a different level from this dreadful performance to complete the salvage job.
After a bright opening in which Danny Welbeck threatened and Arsenal had a penalty claim ignored when Wallace appeared to handle, Monaco kept the Gunners at bay in relative comfort.
As Arsenal's frustration grew, Monaco felt confident enough to move forward with increased ambition and the away goal they would have craved came seven minutes before the break.
Welbeck conceded possession and as Joao Moutinho moved forward he found the impressive Kondogbia, whose 25-yard shot took a decisive deflection off Per Mertesacker to leave keeper David Ospina helpless.
Giroud had been presented with Arsenal's best opportunities but time and again the striker failed to hit the target. In the first half he scooped Hector Bellerin's cross over then he turned Alexis Sanchez's cross wide from six yards.
And how Arsenal paid the price for his profligacy and their own defensive naivety as Monaco doubled their lead after 53 minutes. From their own attack, Mertesacker in particular deserted his defensive post leaving Anthony Martial free to set up the unmarked Berbatov, who steadied himself before thumping a finish high past Ospina.
Giroud's night got worse when he somehow tapped a simple finish over the top after keeper Danijel Subasic fumbled Sanchez's shot - and with the fury of Arsenal's fans ringing in his ears, it was a merciful release when he was replaced by Theo Walcott on the hour.
As Emirates Stadium emptied, Oxlade-Chamberlain, on for Francis Coquelin, curled in a goal from 20 yards that at least offered Arsenal some sort of hope for the second leg.
It was typical of how poor they were, however, that they somehow found themselves caught upfield once more to allow the speedy Ferreira-Carrasco to race clear and beat Ospina for what could be the decisive blow.
- 39BellerinBooked at 74mins
- 34CoquelinBooked at 42minsSubstituted forOxlade-Chamberlainat 68'minutes
- 19CazorlaSubstituted forRosickyat 81'minutes
- 11ÖzilBooked at 87mins
- 12GiroudSubstituted forWalcottat 60'minutes
- 13Fortuna dos Santos
- 21EchiéjiléBooked at 45mins
- 7DirarSubstituted forKurzawaat 82'minutes
- 23MartialSubstituted forBernardo Silvaat 84'minutes
- 8João MoutinhoBooked at 90mins
- 9BerbatovSubstituted forFerreira-Carrascoat 75'minutes
- 12de Carvalho
- 15Bernardo Silva
- Deniz Aytekin
- Shots on Target
Second Half ends, Arsenal 1, Monaco 3.
Goal! Arsenal 1, Monaco 3. Yannick Ferreira-Carrasco (Monaco) right footed shot from the right side of the box to the bottom left corner. Assisted by Bernardo Silva.
Attempt saved. Yannick Ferreira-Carrasco (Monaco) right footed shot from outside the box is saved in the bottom right corner.
Foul by Tomas Rosicky (Arsenal).
Layvin Kurzawa (Monaco) wins a free kick in the attacking half.
João Moutinho (Monaco) is shown the yellow card.
Foul by Tomas Rosicky (Arsenal).
João Moutinho (Monaco) wins a free kick in the attacking half.
Goal! Arsenal 1, Monaco 2. Alex Oxlade-Chamberlain (Arsenal) right footed shot from outside the box to the top right corner following a corner.
Corner, Arsenal. Conceded by João Moutinho.
Corner, Arsenal. Conceded by Danijel Subasic.
Attempt saved. Alexis Sánchez (Arsenal) right footed shot from a difficult angle on the left is saved in the top left corner.
Attempt saved. Yannick Ferreira-Carrasco (Monaco) right footed shot from the right side of the box is saved in the bottom right corner. Assisted by Fabinho.
Mesut Özil (Arsenal) is shown the yellow card.
Corner, Arsenal. Conceded by Aymen Abdennour.
Substitution, Monaco. Bernardo Silva replaces Anthony Martial.
Attempt missed. Alexis Sánchez (Arsenal) right footed shot from the centre of the box is close, but misses to the left following a corner.
Substitution, Monaco. Layvin Kurzawa replaces Nabil Dirar.
Substitution, Arsenal. Tomas Rosicky replaces Santiago Cazorla.