Chelsea suffered UEFA Super Cup humiliation as Radamel Falcao showed them what might have been with a devastating hat-trick to help hand Atletico Madrid a crushing win.
The Blues looked anything but European champions in what was one of their most clueless performances since Roman Abramovich first began his quest for the greatest prize in club football.
The Russian also spent £80 million this summer in a bid to ensure he would not have to wait another eight years for more Champions League glory, but it was the one who got away who came back to haunt him on transfer deadline day as former target Falcao took advantage of some inept defending and tactical naiveti to plunder a first-half treble, with Joao Miranda piling on the misery before Gary Cahill grabbed a consolation.
Falcao's hat-trick was his second in four days and saw him completely outshine Fernando Torres, who endured a nightmare reunion with his boyhood idols just 24 hours after declaring his 18 months of hell was a thing of the past.
The outlook had certainly looked rosy for him and Chelsea at the start of a season which has seen him score three times and storm to the top of the Barclays Premier League.
They did lose the Community Shield to Manchester City, however, and another defeat with a trophy on the line cast doubt on their chances of success this season and manager Roberto Di Matteo's reshaping of the side.
Tonight's game was the last Super Cup match to be played at the Stade Louis II, with the fixture touring the continent from next year.
Chelsea had been involved the first time it came to Monaco in 1998, Di Matteo playing in a famous 1-0 win over Real Madrid.
But staging such a showpiece event at such a hopelessly outmoded venue always seemed to defy logic.
The stadium also held bad as well as good memories for Chelsea, whose eight-year Champions League heartache under Roman Abramovich began there in the 2004 semi-finals.
There were certainly plenty of empty seats in the blue half of what is only an 18,000-seater ground, perhaps not surprising with a Club World Cup trip to Japan on the horizon.
Those who stayed away were doubtless glad they saved their money as Europa League winners Atletico were allowed to create chances almost at will.
Falcao served a fourth-minute warning when his sliding finish hit the crossbar but he made no mistake three minutes later when he raced clear, waited for Petr Cech to commit and dinked the ball beyond the lunging David Luiz on the line and in off the post.
Chelsea did briefly look a threat at the other end, Eden Hazard drilling over, but their midfield had almost no structure and Adrian Lopez and Arda Turan both went close before Falcao struck again in the 18th minute.
Unbelievably, the Blues defence simply stood off one of the world's most lethal finishers as he curled a delicious 15-yard shot into the top corner.
Chelsea now needed the kind of comeback that helped them secure European glory last season but there was no discipline to their attacking and Cech saved from Gabi after Atletico found themselves five on three.
Falcao hit the woodwork for the second time when he threw his head at Lopez's air-shot only to see it hit the post - but he completed a deserved hat-trick moments before half-time when Turan was allowed to run 60 yards unchallenged and squared for the unmarked striker to finish.
Torres's first real attempt of the game in the 50th minute was almost laughable by comparison as Chelsea brought on Oscar for Ramires at the restart.
The change failed to have the desired effect as Atletico made it 4-0 on the hour mark, Miranda poking Mario Suarez's lay-off home.
Jorge Koke's crossed free-kick almost went straight through but was saved by Cech before Cahill drilled home after Atletico failed to clear Frank Lampard's corner.
The Spaniards looked more than capable of restoring their four-goal cushion and David Luiz even turned Emre Belozoglu's cross against his own post in stoppage-time.