There was an odd interlude at Stamford Bridge with 76 minutes gone and the score still 0-0, one of those moments where suddenly your brain seems to be on inside out, like trying to walk the wrong way down an escalator.

Tottenham had a corner on the left-hand side, in a game that had felt to that point like an extended practice session, a refinement of systems, the football equivalent of watching two middle-aged men methodically emptying the dishwasher, adding salt, descaling the hoses, tutting over knives incorrectly slotted, cups in the wrong row.

Fittingly it took a glitch in the coding to break this game open. Austin MacPhee, Chelsea’s set-piece coach, was, as ever, up on his touchline semaphoring his instructions. Except this time he was ordering Chelsea players out of their own box. Get upfield. We need fewer people defending. We must, for some reason, vacate that space and initiate some kind of counterattack chess game.

This had already happened at another corner on 52 minutes. On that occasion ten players were arranged in various upfield positions, leaving just a small gaggle in the box doing the actual try-to-score stuff. The ball landed in one of the huge vacant spaces. Everyone cheered.

Who started this habit? It seems like one of those things that just happens and you don’t know how or why, like driverless cars, or Howard Webb suddenly having his own ref-based TV show. But it was decisive here.

The second corner came howling in right through that vacated area. Again it looked strange, not least on a wet, blustery day, the kind of day where the rain just seems to want to get inside the neck of your coat, up your trouser turn-ups, in your pockets. The ball kept travelling, right through all that open space. At which point Mike Penders punched it into his own net.

MacPhee came to Chelsea in the summer after the club activated his release clause, the most remarkable part of which is that the bloke who waves at corners actually has a release clause (fee: undisclosed). Here his response to the goal was to walk pensively down the touchline, stroking his chin. Hmm, yes, need to log this. Look at the data on that.

To be fair, this was a goalkeeping mistake by Penders, a random variable. Although not really if you zoom out. Penders is not best equipped to deal with no protection, with rain, wind and a soaking ball. Penders is good with his feet, famous for stepping out to play centre-half sometimes at Strasbourg. Maybe he should have been waved upfield by MacPhee to mark the counterattack. Anything but this in fact.

MacPhee’s gambit, now safely in the data bank as Counter-Bluff Own Goal No 34, did at least open up the game. A few minutes later Cole Palmer was sent off for a second yellow after a foul on Conor Gallagher. And on 87 minutes Mathys Tel scored a lovely goal, surging upfield and shooting low inside the near post, signal for Roberto De Zerbi to invade the pitch in a strange capering run, cramped over at the waist, cackling provocatively, like a stylised martial arts pose. Enter: Haemorrhoid Warrior.

Until that point the entire afternoon had felt like an overload of systems-ball. Sometimes games like this are described as a fascinating tactical battle. This was something else, a dull tactical battle. At times in the first half the Stamford Bridge crowd got to watch a press being baited when there was no press, just a bait. Essentially, just people standing around.

By the end two things had happened. First, Chelsea were terrible. Maybe this is still a structural thing. After the years of wild overspend this has now become a high-speed talent trading house, new faces, old faces, faces you didn’t know were there, all simultaneously coming and going. End result: Chelsea had no cutting edge at all here in the absence of João Pedro, an entire system thrown by the lack of a focal point in attack. Danny Welbeck stayed on the bench for whatever reason.

Here Xabi Alonso played Palmer and Morgan Rogers in a strange, liminal forward role, ghost tens, nonexistent nines. There has been a lot of talk about the freedom Alonso likes to give his attack, the hard positional stuff reserved for the block behind. Sometimes freedom’s just another word for standing around in the rain, not sure which run to make.

Chelsea were static all game, lacking in edge, fire or urgency. There was even something a little sad in the crowd reaction on 69 minutes as Palmer earned his first yellow card, signal for a bust-up between the benches, basically a load of men in puffer jackets jostling and prancing. The home crowd leapt up, absolutely delighted to see some kind of edge finally. This is what they like here. In the end people just want to feel something.

Instead Chelsea had kicked off this London derby in cold systems-ball mode, and never got the engine hot. Forty minutes in Palmer had touched the ball eight times, Chelsea were on 27 per cent possession at home to Spurs, and the only real element of tension was the sight of Alonso’s weirdly inadequate golfing blouson steadily saturating with rainwater. Not his only misjudgment of the afternoon.

The second thing, Tottenham were good. Allowed to dominate the ball, and with Mateus Fernandes very good in deep midfield, this turned into their best result of the season, and a huge tick for the manager, who clearly loved every second.

De Zerbi is a funny concept. Wild, passionate, heart on his sleeve. But also obsessed with patterns and systems. He’s basically wildly excited about maths. But he was great to watch here. On the hour mark something complex happened in his team’s movements. Someone stood in the wrong space. A chance to swarm-press was passed up.

In response De Zerbi leapt in the air and let out a strange baying noise, the sound of an alpaca being garrotted. Moments later, Omar Marmoush passed straight to a Chelsea player and De Zerbi didn’t even flinch. We see things you’ll never see.

For a while James Maddison seemed to be playing a different game to everyone else, one where you’re allowed to make forward passes, carry the ball and make the game up in front of you a little. With 49 minutes gone he sat down in the centre-circle, his game done, which will be a concern. But this was still an excellent afternoon for De Zerbi’s Spurs; albeit one that turned on a missed punch and a moment of unnecessary helicopter coaching.