The Yellow Brick Road is a construction familiar to all, but on Tuesday it was a yellow brick wall that became famous.
Guus Hiddink, the same wizard of Oz who guided Australia to the 2006 World Cup finals, will take particular pleasure from another tactical triumph. His side hold the distinction of being the only team to stop Barcelona scoring at home this season.
Peering over the edifice of yellow shirts was Petr Cech, who, after a calamitous performance against Liverpool in the previous round of the Champions League, and a less than encouraging start on Tuesday, lived up to the reputation that he has been in danger of dismantling.
But, had Cech not saved so expertly from first Samuel Eto’o and then Alexander Hleb in the second half, and had Bojan Krkic not lost his bearings when a simple headed goal beckoned, Chelsea would be in a position most perilous.
Hiddink would be seeming less like a man with a tactical mastermind than someone who had inflicted on to his team a tactical straitjacket that so constrained as to make that most precious of commodities, an away goal in Europe, out of reach.
John Obi Mikel and Michael Ballack were instructed not to vacate their own half of the pitch, while Frank Lampard did not have a shot at goal. Didier Drogba was the loneliest of lone strikers.
Hiddink is willingly treading a fine line.
Manchester United trod it perfectly last year, defeating Barcelona 1-0 at Old Trafford after a goalless draw in the first leg, but it is difficult to envisage the Catalans failing to score for a fourth successive game against English opposition.
Although Lionel Messi disappointed and Samuel Eto’o and Thierry Henry were frustratingly indecisive on Tuesday, there can be no doubting the potency of such a formidable threesome.
Chelsea believe they are on the road to the Champions League final, a path paved by yellow bricks intricately laid, but without an away goal stowed away from the first leg, it may yet lead to unexpected curvatures.