While Tuchel’s Chelsea reign now has real lift off, Spurs continue to flounder and have lost three successive Premier League matches for the first time since November 2012, when Andre Villas-Boas was at the helm.
Victory takes Chelsea above Everton and up to sixth place in the table, two points behind West Ham in fifth and only four behind fourth-placed Liverpool.
Spurs – still without injured talisman Harry Kane – remain eighth having now played a game more than Aston Villa, who are only a point behind Mourinho’s men. Arsenal are only two points behind in 10th, but have played a game more.
It was a wretched first-half display from Tottenham, who also lost at home to Liverpool seven days ago before an abject loss at Brighton on Sunday.
The decisive moment came after 24 minutes, when Dier brought down Werner inside the box and Jorginho dispensed with his usual hop and skip routine to powerfully lash home a spot-kick past the despairing dive of Hugo Lloris, who guessed the right way but could do nothing to keep out the Italian’s effort.
Chelsea were dominant before the interval with Frank Lampard favourite Mason Mount running things in midfield and both wing-backs pushed on high, but the visitors struggled to fashion many more clear-cut chances – aside from Werner heading wide in the opening seconds – and lost veteran defender Thiago Silva to a thigh injury.
Tottenham were improved after the break as they looked to deny Chelsea back-to-back wins for the first time since November after last week’s triumph over Burnley, but needed Serge Aurier – who headed narrowly wide in the first half – to make a superb last-ditch tackle on Werner to prevent a second goal.
Hugo Lloris was brave to deny substitute Christian Pulisic and then had to improvise to deal with a bizarre pass back from Dier.
The Frenchman also got down well to save a low strike from the influential Mount, while Erik Lamela’s curling effort was parried by Chelsea goalkeeper Edouard Mendy.
Chelsea still held that narrow lead heading into the final 10 minutes on a rain-soaked night in north London, with Lucas Moura firing well over, Benfica loanee Carlos Vinicius heading Aurier’s cross agonisingly wide on his first Premier League start and Dier bending a long-range free-kick comfortably beyond the post.
More questions for Mourinho as he slumped to back-to-back home league losses for the first time in his English top-flight career.