Tuchel must, of course, take some responsibility for the defensive downturn. One could sympathise with Azpilicueta struggling to hit his top form after being shifted to left wing-back in place of Marcos Alonso.

And there was an acknowledgement from Tuchel that he had got things wrong, as he made a double change at the break by sending on Mateo Kovacic to replace Christensen and Hakim Ziyech to take over from N’Golo Kante.

Kante had been the inspiration behind Chelsea’s Champions League success last season, along with Edouard Mendy, but the goalkeeper suffered what might have been his worst moment as a Chelsea player less than a minute into the second period.

Teams appear to have twigged that Mendy is not altogether comfortable with the ball at his feet. Having almost gifted Brentford striker Ivan Toney a goal at the weekend, the Senegal international horribly underhit an intended pass to Rudiger and Benzema completed his hat-trick in the easiest of manners.

Benzema deserved his slice of good fortune having sprinted from inside his own area to put pressure on Mendy and Chelsea can expect more teams to now target their goalkeeper when the ball is at his feet.

This time last year Chelsea bounced back from a shock defeat to West Bromwich Albion to beat Porto in the Champions League, but Wednesday night was a continuation of what had gone wrong at the weekend, rather than a reaction to it. 

A furious Tuchel tried again to provoke a shift in momentum with another two changes from the bench, with Romelu Lukaku and Ruben Loftus-Cheek sent on in place of Christian Pulisic and Jorginho.

The home side rallied and the crowd, to their credit, responded, but Lukaku missed a sitter with his head and it was impossible not to draw comparisons between Chelsea’s club record signing and Madrid’s number nine.

Benzema will certainly be looking forward to facing Chelsea’s defenders again in next week’s second leg and possibly giving Christensen and Co the runaround in next season’s Clasico.