Trevoh Chalobah and Nicolas Jackson scored as Chelsea dealt a huge blow to Tottenham's Champions League hopes, recording a 2-0 derby win over Mauricio Pochettino's old club at Stamford Bridge.
Exactly eight years on from the memorable "Battle of the Bridge" between the teams, which saw nine Spurs players booked in a fiery 2-2 draw that confirmed Leicester City as champions, Chelsea inflicted more woe upon their rivals.
Spurs paid for lacklustre set-piece defending midway through the first half as Chalobah headed Conor Gallagher's free-kick home, then Jackson pounced when Cole Palmer rattled the crossbar from another dead ball 72 minutes in.
Ange Postecoglou's side were far from their free-flowing best and have now lost three straight Premier League games. They stay fifth, seven points behind fourth-placed Aston Villa with just one game in hand.
Chelsea, meanwhile, climb above West Ham into eighth, just three points adrift of Manchester United in sixth.
The Blues went agonisingly close to a fifth-minute lead as Jackson raced through on goal to slot his effort under Guglielmo Vicario, but Micky van de Ven raced back to hook it off the line and Palmer could not sort his feet out on the rebound.
Chelsea were ahead after 24 minutes, though, as Chalobah met Gallagher's deep free-kick with a looping header into the top-right corner, the goal being confirmed by VAR following a check for a possible foul by Marc Cucurella.
Mykhailo Mudryk went close with a curling effort as Tottenham continued to toil, the visitors' best chance of the first half coming when Cristian Romero headed Pedro Porro's free-kick wide.
Ange Postecoglou cut an animated figure before half-time, and his side improved after the restart, but Chelsea could have had a second when Palmer shot over at the end of a promising break.
Chelsea did double their advantage with 18 minutes to play, the opportunistic Jackson heading into an unguarded net after Palmer's free-kick clattered off the woodwork with Vicario at full stretch.
Tottenham never looked like responding from there, and they now need a minor miracle to secure a top-four finish.
Pochettino haunts former employers
Having also overseen Chelsea's memorable 4-1 win in November's return fixture at the Tottenham Hotspur Stadium, Pochettino completed a league double over his former employers.
He is the first coach to ever beat Spurs home and away in a single Premier League campaign having previously managed them in the competition.
The Argentine's first season at Stamford Bridge may not have gone entirely to plan, but there may just be green shoots of recovery emerging in the closing weeks of the campaign.
Having endured a run of one win in 14 home Premier League games between March and November last year (seven draws, six losses), Chelsea – who face West Ham next – have now won eight of their last 10 on their own turf (one draw, one defeat).
Set-pieces costing Spurs
Tottenham have a set-piece problem. Arsenal ruthlessly exploited some slack marking from their neighbours to score two goals from corners in Sunday's north London derby, and on Thursday, it was two free-kicks that undid Postecoglou's men.
Prior to this game, Spurs had conceded 12 goals from set-pieces, excluding penalties, in the Premier League this season. Only Manchester United (15.3) and Burnley (14.9) had allowed opponents a higher cumulative expected goals (xG) figure from such situations than their 14.3.
They did not learn their lesson, Emerson Royal and Brennan Johnson getting nowhere near Chalobah as he headed home from a routine delivery to the back post for the opener.
Those fine margins could prove incredibly costly, with Tottenham now a long way adrift of top-four rivals Aston Villa with daunting fixtures against Liverpool and Manchester City still to come.