With around 25 minutes to go at Stamford Bridge, Timo Werner’s luck finally turned. Mateo Kovacic slid a pass into the left channel, whereupon Werner gathered the ball in his gangly, maladroit stride and began the lengthy, protracted process of bringing it under control.

Somewhere amid the tangle of legs and leather, a tackle was attempted by Wesley Fofana. Why Fofana did this remains a puzzling matter, given that on recent experience the most effective way of winning the ball from Werner is simply to let him tackle himself. Still, it was a moment of well-deserved fortune for Chelsea’s ill-starred striker, albeit one largely generated by his own elephantine clumsiness.

Perhaps it was the moment Chelsea’s luck turned as well. Having toiled fruitlessly for 45 minutes, Jorginho’s penalty put them two goals up, a cushion they ended up needing. Kelechi Iheanacho’s sudden goal offered Leicester a lifeline, and in a surprisingly chaotic finale the visitors could quite conceivably have stolen a point, despite looking for most of the game like a team still tipsy on their Cup final champagne.

In essence, those hairy last 15 minutes (plus eight added on) encapsulated the curious fragility of Chelsea at the moment: a team with a Champions League final to look forward to, and qualification for next year’s competition in their grasp, and yet with only the barest idea of how they’ve managed to achieve it.

How much of this is genuine, sustainable improvement? And how much of it is good feelings, pretty illusions and regression to the mean: the footballing equivalent of switching the machine off and on again?

Certainly the raw numbers are hard to argue with. It’s now 13 games since Chelsea conceded more than once. The only goals scored against them this month have been via defensive errors (Jorginho, Andreas Christensen, Reece James here) and a 30-yard screamer from Youri Tielemans at Wembley. Even in this supposedly tight victory, Chelsea could easily have been out of sight had it not been for an inspired display by Kasper Schmeichel.

Werner thinks he has given his side the lead only for the goal to be ruled out for handball by the Chelsea striker.
Werner thinks he has given his side the lead only for the goal to be ruled out for handball by the Chelsea striker. Photograph: Plumb Images/Leicester City FC/Getty Images

There is a momentum and a buzz to this team, most evident during a first hour in which, roared on by the newly restored crowd, Chelsea tore into the game like it was a fresh bag of crisps, all angular runs and thrilling joyrides. Mason Mount was again one of the best players on the pitch. Ben Chilwell whistled a shot just wide. After one flowing attack, the man rakishly attacking the cross at the back post was none other than César Azpilicueta, like a pensioner trying his first Jagerbomb.

Werner, by contrast, was carrying his own personal raincloud around with him. He had two goals ruled out. He should probably have won a penalty when Tielemans chopped him down in the area. And yet for all the commendable industry and energy he has displayed during his first season in English football, we have perhaps reached a point where it is reasonable to ask whether a £53m forward might eventually offer a little more than this.

Above all you sense that Werner is still somehow out of place here, still playing in an RB Leipzig shirt, still looking up and expecting to see Yussuf Poulsen making the run outside him, Marcel Sabitzer lining up the through ball. And for all Chelsea’s pleasing attacking brio, they still look vaguely at cross-purposes going forward, a team yet to discover a reliable method of putting the ball in the net.

Their last 11 games have produced just 10 goals, a statistic consistent with a team throwing enough individual talent at the wall in the hope that some of it sticks. No real blame can really be attached to Tuchel here: this was perhaps the only way he could have started given the lack of contact time and the demand for immediate improvement. And when they are forced on the back foot, Chelsea still look cussedly tough to break down, that midfield double-pivot collapsing on to the back five like a deadlock.

This is what allows them to maintain the pressure even in their stickier moments: the knowledge that first blood is generally sufficient. Here it came from Antonio Rüdiger, scoring the sort of goal that Werner couldn’t even buy on the dark web, stumbling on to a deflected Chilwell corner and bunting the ball in with his thigh. Jorginho doubled the advantage, and though Leicester threw everything onto the closing minutes the damage had already been done.

On another night perhaps Chelsea might have been thwarted, sucker-punched, made to pay for their profligacy. Over the long run, you’d conclude that this was a team overdue a painful reckoning. Yet somehow this team keeps finding a way, surfing the waves, majestically convinced that things will work out in the end. With two games left in this most capricious of seasons, it might just be enough.