How to beat Chelsea. Step 1: Man-mark Eden Hazard. Step 2: Close down all spare space. Step 3: Hassle and harry, show no respect. Step 4: Score.

Leicester City’s game plan worked to perfection, with the Blues falling to a rare home defeat, and Leicester fans jubilantly heading back to their buses, chanting deliriously.

Hamza Choudhury, or as one Chelsea fan put it on the tube from Fulham Broadway ‘the bloke with the barnet’, kept a cap on Hazard’s movements, while the Foxes as a team kept pestering the Blues to deny the home side their usual possession supremacy in the away half.

Attack after attack fizzled out, thanks to resolute defending (Kasper Schmeichel had relatively little to do), and Leicester repeatedly hit Chelsea on the break with rapid runs and good diagonal balls.

Only Kepa’s excellent reaction keeping maintained the score at 0-1. Actually, 0-2 would have been fairer.

Chelsea went back and forwards, but there were no penetrating down-the-middle runs.

Even bringing on Ruben Loftus-Cheek, Olivier Giroud and Cesc Fabregas during the second half made no difference. Ironically Morrie Sarri spent several minutes of the first half complaining about Leicester’s time-wasting, even with the score at 0-0.

Vardy’s goal came in the 51st minute when James Maddison, the corner-taker and perpetual irritant to Blues players, set up the forward to smash the ball home. Arguably the true turning point, however, was when Wilfred Ndidi’s thunderbolt shot was tipped over by Kepa five minutes before half-time – a pivotal moment.

Chelsea simply cannot weave through the middle of an opposition defence; Sarriball dictates that they build slowly from the back, and keep coming down the sides with lots of little passes.

The trouble is, opponents have sussed this, and react accordingly.

It makes the trip to Watford on Boxing Day look even less certain.