Antonio Conte had stressed before kick-off that Chelsea needed to be perfect in order to beat an exceptional Barcelona side flying high at the top of La Liga and led by the irrepressible Lionel Messi.
“I think that, for sure, we have to play a perfect game against Barcelona if we want to win," Conte said ahead of the game. "I repeat, on paper, you start these two games with one favourite and this is Barcelona.
"I think that they earned the right to be the favourites this season for what they have been doing for many years in football in the world. For us, we have to try to work, to try and do our best.
"Then, at the end of the game, if we are very good to win the game, it will be okay. Otherwise, it means that Barcelona were better than us.”
For all but a few seconds of madness, Chelsea were indeed perfect as they seemed destined for a famous victory following Willian’s second half strike.
Barcelona barely created a chance all game until a wayward pass from Andreas Christensen across his own penalty box was intercepted by Andres Iniesta, allowing Messi to end his goal drought of 730 minutes and eight games against the west London club.
Until that moment with 15 minutes remaining, Conte had produced a tactical masterclass, clearly making good use of the sleep he sacrificed ahead of the match.
Eden Hazard lined up as a false nine supported by Willian and Pedro with their most natural strikers in Alvaro Morata and Olivier Giroud being left on the bench.
Chelsea saw little possession or territory for long periods, just as Conte had predicted, with Barcelona completely dominating the ball and holding almost 70 per cent of the ball. However, they did virtually nothing with it – their only other chance of the game being a tame Paulinho header that went wide.
Indeed, Chelsea created the better chances with Willian and Hazard acting as perfect outlets, carrying the ball up-field and winning free-kicks while also carving out openings.
The pair combined for Chelsea's goal after Willian had earlier hit the post twice with similar efforts from the edge of the penalty area.
In the 62nd minute, Hazard picked up the ball from a corner and played in Willian who curled in a wonderful effort to beat Marc-André ter Stegen.
Barcelona looked unlikely to find a way back into the match as Chelsea smothered them on the edge of the area, with Messi and Luis Suarez having no space to play with. However, a virtually perfect team performance was ruined by an individual mistake by Christensen.
Chelsea's task of going through to the Champions League quarter-finals now looks difficult but not impossible and there is still plenty to play for come March 14 when they go to Camp Nou for the second leg.
Conte won the battle of minds with Ernesto Valverde to show why he is one of the best tactical coaches in the world but it is the Barcelona boss who will sleep well tonight thanks to Messi’s crucial away goal.