LONDON — Chelsea and Tottenham Hotspur battled and scraped for every single inch in an intense London derby in the driving wind and rain at Stamford Bridge on Saturday.

It wasn’t pretty. But Spurs won’t care. For just the second time in 37 attempts they’ve won at Chelsea in the league and are building serious momentum under Roberto De Zerbi.

Here’s a look at what we learned from a tense, tight derby, as Spurs prevailed in the stormy conditions.

Joao Pedro’s absence is a big, big problem for Chelsea

Hearing Joao Pedro was out injured was a big blow for Chelsea. They just couldn’t cope without him. But instead of bringing Danny Welbeck in as a like-for-like replacement and not changing anything else, Alonso decided to overcomplicate things. It did not work. Youngster Quenda came in with Cole Palmer and Morgan Rogers playing as dual false nines to create a 4-2-4 in possession. That left big gaps in midfield and there was too much confusion with Chelsea’s press. Nobody knew what they were doing. If Welbeck had just come in Chelsea would have been less disjointed and had some kind of rhythm. Instead the players seemed to be figuring it out on the fly and that is a big concern. If Joao Pedro is out for a long period of time then Welbeck starting in his place has to be the answer. Chelsea’s entire attacking unit faltered without a spearhead to work off and connect with.

Intense Spurs have lift-off and deserve it

The sight of Roberto De Zerbi stomping his feet in frustration and slamming his hands against his legs is now becoming increasingly familiar. Spurs put in another very promising display, just like they did against Manchester United, Everton and Aston Villa this season, and finally they got the bit of luck they deserved. Spurs zipped the ball around well, were solid in defense and were able to get Mathys Tel and Mohammed Kudus on the ball out wide in dangerous areas with James Maddison and Sandro Tonali dictating the play in midfield and Mateus Fernandes providing brilliant energy alongside them. The intensity and organization was top notch and this is a statement win for Spurs and De Zerbi. When Tel’s superb strike made it 2-0 late on he ran onto the pitch in delight and did a happy dance. Spurs have clearly put in the hard work and are tough to play against and are really intense and precise with their press. Every single player knows what they should do and as injuries clear up, De Zerbi will have even more options and Spurs will get even better. There is real momentum building under De Zerbi.

Conditions impacted the game in a big way, as Penders has full debut to forget

There’s no doubt the conditions had a huge say in this game. Chelsea weren’t able to get their silky playmakers on the ball enough and the swirling wind and rain suited Spurs who didn’t mind going more direct and playing out wide. Of course, the two big moments in the second half also saw the conditions play a big part. Young goalkeeper Mike Penders, making his first Premier League start, came to punch a corner and got it all wrong as the ball slid off his fist and went in for an own goal. Chelsea’s fans in the stands tried to play the linesman for missing an offside, but that was on Penders as the conditions got an assist. Then Cole Palmer slid in and left his foot in on Conor Gallagher and was deservedly shown a second yellow and sent off for a naughty challenge. Penders, 21, will now have to pick himself up and go again, with Emiliano Martinez out for many more weeks. The Belgian knew it was a howler but he made some decent stops to keep Chelsea in it. This defeat was about way more than one goalkeeping error, but it came at a critical moment.