Following their third straight loss, fifth-place Tottenham is now seven points behind fourth-place Aston Villa, following losses to Arsenal and Newcastle.
Tottenham’s hopes of making it into the Champions League were severely damaged on Thursday when Chelsea defeated their faltering London rivals 2-0.
Chelsea took the lead at Stamford Bridge in the first half thanks to a goal from Trevoh Chalobah, his first since March 2022.
The much-maligned Nicolas Jackson scored his 14th goal of a challenging debut season with the Blues in the closing minutes to seal the victory.
Following their third straight loss, fifth-place Tottenham is now seven points behind fourth-place Aston Villa, following losses to Arsenal and Newcastle.
Villa has three games remaining, while Tottenham has four, thus the north Londoners are outsiders to finish in the top four of the Premier League.
It was another painful setback for Tottenham, who have squandered the good will built by Postecoglou for much of the Australian’s first season in charge.
While Postecoglou licks his wounds, Chelsea boss Mauricio Pochettino enjoyed a second win over his former club this season following the 4-1 success in November.
Pochettino had irritated Chelsea fans by admitting he couldn’t “hide his emotions” for the club he managed for five years and led to the 2019 Champions League final.
But he put those feelings aside to provide the result they wanted, keeping alive eighth-placed Chelsea’s hopes of qualifying for Europe and making it just one defeat in 34 home league games against Tottenham.
Postecoglou had criticised Tottenham’s sloppy performance in Sunday’s 3-2 defeat against Arsenal and responded by making five changes, with Richarlison brought in and James Maddison dropped.
But in Pochettino’s 400th match in English football, the Chelsea manager should have been celebrating a goal inside five minutes.
Jackson sprinted into the Tottenham area for a shot that went under Guglielmo Vicario but lacked the power to beat Mickey van de Ven’s clearance off the line, with Cole Palmer somehow scooping the loose ball over from close-range.
Moments later, Chelsea winger Noni Madueke embarked on a dynamic run before firing just over from the edge of the area.
Four of the five goals conceded by Tottenham in their previous two games had come from set-pieces and they were punished for more woeful dead-ball marking in the 24th minute.
Conor Gallagher’s free-kick looped into the area and Chalobah was left unmarked to power a superb header over Vicario from 12 yards.
That made it 22 goals conceded from set plays in league games by Postecoglou’s creaky defence this term.
Tottenham claimed Chelsea defender Marc Cucurella had blocked Brennan Johnson from marking Chalobah, but VAR ignored their protests.
Mykhailo Mudryk’s deflected strike was held by Vicario before the Ukraine winger curled narrowly wide as Chelsea pushed for a second goal.
Undone by their set-piece frailties, Tottenham almost took advantage of Chelsea’s defensive deficiencies with a Cristian Romero header that clipped the post from Pedro Porro’s free-kick.
Postecoglou looked increasingly irate by the half-time whistle and his chastened players responded to their manager’s frustration with a more lively second half display.
Porro’s drive from a tight angle forced Djordje Petrovic to save in Tottenham’s most threatening moment.
But Chelsea landed the knockout punch in the 72nd minute.
Palmer’s fierce free-kick cannoned down off the bar towards Jackson, who reacted quickest to head home from six yards.