LONDON (AFP) - Avram Grant insists Chelsea will do whatever it takes to keep Frank Lampard after the midfielder eased the pressure on his beleaguered boss.

Grant desperately needed a convincing victory against Derby on Wednesday to relieve the angst enveloping Stamford Bridge since his side's humiliating FA Cup exit at Barnsley.

So the Israeli must have thanked his lucky stars that the Blues demolished woeful Derby 6-1 thanks in large part to Lampard's remarkable four-goal haul.

Lampard's goal spree was also perfectly timed after reports the Chelsea's hierarchy were considering selling the England star to fund a move for Werder Bremen's Diego.

The Chelsea icon is yet to agree a new contract after postponing negotiations until the end of the season. But Grant has no doubts Lampard will extend his stay at Chelsea well into the future.

"We plan everything for next season and I can tell you Frank will stay at Chelsea. I am sure about this. Frank said he wants to stay and Chelsea wants Frank," Grant said.

"I know you will ask me this every few weeks but what I told you three months ago I say again.

"The club wants him to stay, he wants to stay so nothing changed. About negotiations, it is not my area."

Lampard has now scored 17 goals this season and his value to Grant's side is surely too great to countenance letting him leave.

"Frank is a very important player for the team and he is having a very good season. Any player who plays like this is not easy to replace," Grant said.

When he is playing you know he can always score. What can I say that I didn't already say about him?"

Lampard started the rout of the rock-bottom Rams when he slotted home a penalty after being tripped by Dean Leacock.

Salomon Kalou added the second after Derby goalkeeper Roy Carroll charged off his line to clear, but succeeded only in tackling the ball straight to the Ivory Coast striker.

Lampard tapped-in Chelsea's third goal early in the second half before Joe Cole followed up Nicolas Anelka's shot to claim the fourth.

Derby were completely out of their depth in this company and it was no surprise to see the hosts boost their goal difference as well as Grant's morale.

Lampard drove in the fifth from the edge of the area and there were still 18 minutes left when he got the sixth,

David Jones replied for Derby a minute later but Paul Jewell's side could hardly claim it was a consolation.

Grant's team are now five points behind league leaders Arsenal with a game in hand. The Gunners still have to visit Stamford Bridge later this month so a Chelsea title challenge cannot be dismissed just yet.

"If we play like we have in the last few league games, who knows. Anything can happen," Grant added.

"I can tell you we will fight until the end. I never give up and I will not start now."

Derby have been destined for a quick return to the Championship for months. Their only concern now is to avoid becoming statistically the worst team in Premier League history.

This wasn't even their heaviest defeat of a miserable campaign - Liverpool inflicted a 6-0 hammering in September - and Jewell made it clear few of this squad would survive into next season.

"I've sat there for 90 minutes squirming in my seat," Jewell said. "We've got a losing mentality at the football club and I've got to change that completely over the course of the close-season.

"I've got every confidence I can do that. The personnel will be different and we will have a different mentality. I can't wait for that to happen.

"It doesn't take a rocket scientist to know that some of them aren't going to be here next season."