A four-goal super show from Frank Lampard re-ignited the debate over his long-term future as Chelsea moved within five points of Barclays Premier League leaders Arsenal.

Lampard put himself back in the spotlight as the Blues stunned Derby by bouncing back in emphatic style from their shock FA Cup quarter-final exit to Barnsley.

The England midfielder was left out against the Tykes but was superb throughout as the Rams were left in deeper trouble at the foot of the table.

Salomon Kalou and Joe Cole were also on target for Avram Grant's side.

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, but his shot hit the post.

Derby struggled to deal with Chelsea's opening onslaught, which bordered on the relentless in the opening 10 minutes.

Joe Cole almost caught out Roy Carroll in the 11th minute when his deep cross eluded the Derby goalkeeper completely.

Fortunately for County, the ball bounced off Moore's back and into Carroll's hands.

Derby were forced to make a substitution in the 15th minute when Dean Leacock replaced injured Alan Stubbs at the heart of the defence.

Chelsea had a goal ruled out for offside in the 19th minute after 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.

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 got up to send Carroll the wrong way from the resultant spot-kick.

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.

They were quick to shut down any space Derby made for themselves and attacked en masse when they regained possession.

It was no surprise when Chelsea added a second goal three minutes before half-time.

But Derby boss Paul Jewell would have been far from happy with the way his side conceded the second.

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.

But Chelsea's desire to eradicate the memory of Barnsley was further underlined when 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.

Lampard's contribution had been immense but it was about to get even better.

But it was Joe Cole who finally 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.

But Lampard was not to be denied and he added his fourth in the 72nd minute before Derby scored a consolation goal moments later through substitute David Jones.

Teams

Chelsea Cudicini, Ferreira, Carvalho, Terry, Ashley Cole,Ballack (Drogba 67), Makelele (Essien 73), Lampard,Joe Cole (Shevchenko 74), Anelka, Kalou.

Subs Not Used: Hilario, Alex.

Goals: Lampard 28 pen, Kalou 42, Lampard 57, Joe Cole 64,

Lampard 66, 72.

Derby Carroll, Edworthy, Stubbs (Leacock 16), Moore, McEveley,Sterjovski, Ghaly (Earnshaw 52), Savage, Pearson,Lewis (Jones 58), Miller.

Subs Not Used: Price, Villa.

Booked: McEveley.

Goals: Jones 73.

Att: 39,447

Ref: Chris Foy (Merseyside).