A four-goal haul from Frank Lampard saw Chelsea close the gap on Barclays Premier League leaders Arsenal to just five points.
The England midfielder scored a second-half hat-trick as Derby County were destroyed with a performance of power and pace from Avram Grant's side.
Lampard put the Blues in front from the penalty spot in the 28th minute and Salomon Kalou added a second before half-time.
The England midfielder then struck after 57, 65 and 72 minutes with Joe Cole managing to get on the scoresheet in between.
Chelsea almost took the lead in the third minute when Derby defender Darren Moore failed to clear the ball and Nicolas Anelka and Kalou combined to set-up Lampard.
Lampard found himself in space on the edge of the six-yard box but instead of putting Chelsea in front, Lampard saw his shot cannon back off the inside of the far post.
Joe Cole almost caught out Roy Carroll in the 11th minute when the Chelsea midfielder's deep cross eluded the Derby goalkeeper completely. Fortunately for County, the ball bounced off Moore's back and into Carroll's hands.
no surprise
Chelsea had a goal ruled out for offside in the 19th minute when Joe Cole fed Michael Ballack on the edge of the penalty area and the Germany captain sent the ball into the corner of the net - only for his effort to be disallowed by referee Chris Foy.
But Derby remained under intense pressure and Joe Cole sent another effort well wide after Kalou and Ashley Cole combined to engineer an opening.
Chelsea went in front in the 28th minute when Lampard was upended by substitute Leacock and the England midfielder sent Carroll the wrong way from the resultant spot-kick.
It was Lampard's 14th goal of the season and was just reward for Chelsea's endeavours.
Chelsea continued to pour forward at every opportunity and Lampard should have done better with a shot from the edge of the penalty area in the 35th minute.
But the midfielder was off balance as he struck the ball and it sailed into the crowd behind Carroll's goal. It was no surprise when Chelsea added a second goal three minutes before half-time.
But Derby manager Paul Jewell would have been far from happy with the way his side conceded the second.
empty net
Lampard found Anelka racing down the middle but Carroll and Moore were guilty of hesitating and when the County keeper's clearance landed at the feet of Kalou, the Chelsea striker hit the ball into an empty net from 25 yards.
Anelka should have made it three for Chelsea in the 51st minute but he headed a cross from Kalou wide of the target from six yards.
Lampard scored his second of the night in the 57th minute following a superb run and cross from Joe Cole.
Moments later Ballack tried his luck from 25 yards but Carroll dealt with the threat in a comfortable fashion.
Joe Cole got on the score-sheet himself in the 64th minute. Anelka's initial shot was saved by Carroll but the ball ran into the path of Cole who applied the necessary finish into an empty net.
A minute later, Lampard grabbed his hat-trick and Chelsea's fifth with a 25-yard effort.
It was all Chelsea now and in the 68th minute Carroll had to be at his best to prevent Kalou from making it six.
Lampard bagged his fourth of the night in the 72nd minute and Derby responded with a goal from substitute David Jones seconds later.
