Chelsea returned to the top of the Premier League as they recovered from a goal down to beat Tottenham Hotspur at Stamford Bridge and notch a seventh win a row.
Spurs, who saw their unbeaten league record ended, began the game brightly with Chelsea -- who had won their last six games without conceding a goal -- contributing to their own early jitters as David Luiz gave the ball away in a dangerous position.
They had the ball in the Chelsea net after only eight minutes when Harry Kane pounced, only for an offside flag to deny him.
But with the Blues struggling to settle and Spurs keeping them under pressure, the visitors took the lead in stunning style with 11 minutes on the clock.
Midfielder Christian Eriksen smashed home a superb finish from outside the area, leaving home goalkeeper Thibaut Courtois helpless as Chelsea conceded their first Premier League goal since the end of September.
As Chelsea's frustrations grew, Luiz was booked for a clumsy challenge on Kane and Spurs soon threatened again when some neat passing football opened the way for Victor Wanyama to shoot over the top from outside the area.
Luiz tried his luck from a free kick but sent the ball far too close to Tottenham goalkeeper Hugo Lloris, and Courtois was in action at the other end as he tipped over a fierce drive from Kane.
Chelsea were struggling to create any danger of their own and soon had another reason to worry as Eriksen latched on to a pass but could not replicate his first attempt, firing well wide.
But, out of nothing, Antonio Conte's side levelled a minute before the break with another goal of outstanding quality.
Pedro turned into space just outside the area after a flowing move involving Nemanja Matic and curled a dipping effort beyond Lloris to leave the sides all square going into the break.
Home midfielder N'Golo Kante sent a fierce strike straight at Lloris within moments of the restart as Chelsea began the second half in a far more positive fashion than they did the first.
And they did not have to wait long to take the lead as Victor Moses was left all alone in the area to steer the ball home via Lloris and Jan Vertonghen on the line after Costa's fine run and low cross had completely unhinged the visiting defence with 51 minutes gone.
It should have been 3-1 moments later when another Costa cross found Marcos Alonso unattended on the penalty spot, but he lashed the ball high into the Shed End.
In a reverse of much of the first period, Spurs were failing to create much threat, although Eriksen almost improvised a fine equaliser when he steered Kane's lofted cutback towards goal but found Courtois in the way.
Costa failed to get the right connection when a cross found him inside the penalty area.
As the game entered the final 10 minutes Spurs began to increase the pressure, winning a string of corners as the home side sat back and defended their lead.
Eriksen forced Courtois to come out and punch a dangerous free kick clear, and as the pressure grew an over-hit Eric Dier cross had Courtois worried for a moment as it looped over him and past the far post.
Willian fired over after another excellent run and low cross from Costa and, as the game entered three minutes of stoppage time, Costa made another run down a flank before seeing his attempt to find Oscar with another low cross was cut out Tottenham.