Manchester United chose the wrong day to produce one of their worst hour's football of the season, much as Chelsea had done when sliding out of the Champions' League to Jose Mourinho's Internazionale.
Now, however, that loss looks a blessing in disguise. Carlo Ancelotti was able to enjoy a free week while United were exerting themselves against Bayern Munich, and will do so again during this week's second legs, concentrating exclusively on Saturday's FA Cup semi-final with Aston Villa.
Ancelotti used his time well, planning an attacking approach and a high tempo from the start. His midfield trio spread the play wide to effective wingers in Joe Cole and Florent Malouda, well supported by the full-backs Paulo Ferreira and Yuri Zhirkov. Frank Lampard and Deco were excellent, and once Cole's audacious flick had secured the lead, Deco in particular used his experience to slow the game by simply keeping possession. His team were helped in that ambition by United's careless tendency to give the ball back to them.
After a first half in which one low drive by Patrice Evra, comfortably held, was the champions' only shot on target, it is reasonable to assume that Sir Alex Ferguson's half-time chat was lively. It still took another quarter of an hour for United to exert serious pressure, but Chelsea withstood it before breaking out to snatch a second goal. This being the Premier League, there was controversy about it, Didier Drogba standing a yard offside before striking his shot.
Each side was also denied a convincing penalty claim and Chelsea protested that Federico Macheda used his hand in scrambling a goal to fan the embers of United's dying hopes. It was significant, however, that they needed Macheda to take a hand – or a chest, whichever it was – in the absence of Wayne Rooney.
Dimitar Berbatov's rather less dynamic qualities were insufficient here and it may be that Macheda will have to start alongside him at Blackburn next Sunday in the hope that United can stay in contention until their talisman and leading goalscorer returns, possibly for the huge date with Manchester City on Saturday week. What is undeniable is that they have now lost seven times this season, a handicap that no club has ever overcome to win the Premier League.
If Drogba is the one serious contender to Rooney as player of the year, Chelsea can still manage without him. After the 7-1 romp against Aston Villa last weekend, Ancelotti kept an unchanged team, knowing that Drogba had not trained fully but could be called upon when required. Sticking to Nicolas Anelka in attack and Mourinho's old 4-3-3 formation also allowed Cole (pictured right) the sort of opportunity he is desperate to grasp as the World Cup looms. In front of Fabio Capello's assistant Franco Baldini, he seized it, not least with his intervention in the 20th minute.
Entitled to be satisfied with their efforts up to that point, Chelsea then received some tangible reward as Malouda broke down the left, away from Antonio Valencia and past Darren Fletcher to the byline. His cutback was the type to threaten danger and Cole took advantage with an improvised flick that suggested any crisis of confidence is over. It was only his second Chelsea goal in his last 45 games.
Petr Cech's easy catch from Evra's drive was the only save by either goalkeeper until that point and the only other incidents before half-time were yellow cards (for Paul Scholes and Gary Neville) and controversies in the penalty area. Mike Dean had awarded 16 penalties in 24 games before yesterday, by far the highest total of any Premier League referee; Blackburn's Martin Olsson having claimed that he used that knowledge in taking a dive against Burnley to win a decision.
South Korea's Park Ji-Sung is not cut from the same shabby cloth, but he too may have exaggerated his fall after Zhirkov caught his leg inside the area. Dean was unmoved and remained so after an even more blatant foul by Neville, charging Anelka in the chest and down to the ground.
Chastened or not by Ferguson's talking-to, United could still have fallen further behind two minutes into the second half. Cole's fine pass put in Ferreira, who could not decide whether to shoot or cross and produced a feeble combination of the two options.
At last, however, the home side began to press and then to threaten. Park was off balance as he shot into the Stretford End, Berbatov headed wide and then too high, and it was now Chelsea names – Deco's and Cole's – being noted by the referee.
Drogba and Macheda were among the clutch of substitutes introduced and each had a significant part to play. In the 78th minute Salomon Kalou, another replacement, played in Drogba, who deceived the referee's assistant with his run and then Edwin van der Sar with his shot. Two minutes later another pair of fresh legs, these belonging to United's Nani, sped down the left for a cross that Cech could only push into the body of Macheda, Chelsea appealing in vain that it was a hand that propelled the ball over the line.
A frantic finish was thus guaranteed but Berbatov's hooked shot at Cech was the nearest thing to one of United's famous late goals. Once again they had ended a Champions' League week in defeat and this may prove the most costly of all.
Referee: Mike Dean
Man of the match: Malouda