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 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.