Chelsea came from 2-0 down to beat Tottenham 4-3 on Sunday and go second in the Premier League thanks to two Cole Palmer penalties.
Dominic Solanke and Dejan Kulusevski gave under-fire Spurs boss Ange Postecoglou a dream start.
But his cavalier attacking approach will come under more scrutiny as Chelsea roared back to extend their unbeaten Premier League run to seven games.
Jadon Sancho gave the visitors a foothold before they dominated the second half with Palmer twice cool from the spot, either side of Enzo Fernandez's strike.
Chelsea close to within four points of leaders Liverpool, who have a game in hand after their visit to Everton on Saturday was postponed due to high winds.
Son Heung-min's 96th-minute goal was little consolation for Spurs who have won just once in seven games and remain 11th in the table.
Chelsea defender Levi Colwill told Sky Sports: "It means everything to beat our rivals. It was a great win. We knew it was going to be tough but we trust that when we play our football it will be fine.
"We have amazing players like Cole [Palmer]. When he scores big goals, he calms us down and hopefully it continues in the future. We were 2-0 down but none of the players were panicking, we knew we would create chances.
"We have still got a lot to improve on, when we're ready to push for a title we won't be 2-0 down in the first 10 minutes. That's the level we need to be at and that's what we need to keep working on."
Postecoglou was involved in an angry confrontation with his own supporters after a dismal display in a 1-0 defeat to Bournemouth on Thursday.
Spurs have often saved their best for the biggest games this season, beating Manchester City twice and cruising to a 3-0 win at Manchester United early in the campaign.
Postecoglou's men flew out of the traps to leave an in-form Chelsea chasing shadows in the early stages.
Solanke stole in at the near post to turn in Brennan Johnson's cross to open the scoring.
Kulusevski then meandered along the edge of the Blues' box before firing low past Robert Sanchez to make it 2-0 inside 11 minutes.
Sancho scored his first Chelsea goal in a 5-1 romp at bottom-of-the-table Southampton in midweek to earn himself a start.
The Manchester United loanee quickly got the visitors back in the game with a brilliant long-range strike past Fraser Forster.
Somehow that was the end of the scoring in a frantic, fast-paced first 45 minutes that had chances aplenty at both ends.
Pape Sarr headed off the crossbar and Solanke should have converted Son's cross to extend Tottenham's lead.
At the other end, Forster stretched his long limbs to deny Palmer and Pedro Neto an equaliser.
Both sides were also fortunate to get to the break with 11 men still on the field.
Moises Caicedo's studs-up challenge on Sarr was deemed not to have excessive force by the VAR official.
Likewise, Kulusevski escaped further punishment for a stray elbow on Romeo Lavia.
Led by Palmer, Chelsea took control after the break to rub more salt in Spurs wounds and leave Postecoglou's future up for debate.
The former Australia boss bemoaned this week how his side often "shoot themselves in the foot" and so it proved for the vital fourth goal.
Yves Bissouma unnecessarily dived in on Caicedo to concede a penalty, which Palmer coolly dispatched to level.
Palmer had a major role in Chelsea's third as well as his shot was blocked after a weaving run into the Spurs box, but the ball fell for Fernandez to blast home from the edge of the area.
To compound Tottenham's woes, both their preferred centre-back pairing of Cristian Romero and Micky van de Ven both had to be replaced after being rushed back from injury to start.
Another moment of madness secured the points when Sarr barged Palmer over inside the area.
The England international this time impudently dinked the spot-kick Panenka-style down the middle of Forster's goal.
Son turned in James Maddison's cross to set up a nervy finale.
But Enzo Maresca's men held on to close in on Liverpool and further their case as unexpected contenders for the title.
