Arsenal moved four points clear at the top of the Premiership and within three points of the title after Frenchman Emmanuel Petit scored a scorching 35th minute goal.

But the Gunners were left with a major worry over injured Dutch ace Dennis Bergkamp who, having missed a penalty, limped off with a hamstring injury after just past the half hour.

Arsene Wenger's team clung on through a nervous last five minutes to set up a Sunday special against Everton when another win will leave Manchester United helpless to prevent the Gunners taking the crown.

But the big worry is now over 22-goal Bergkamp who looked in severe discomfort as he hobbled off at a dramatic moment in a rugged clash with Jim Smith's wound up Derby team who battled for their pride but in the end collected only five bookings.

Petit's decisive strike came five minutes after Bergkamp's exit, a thunderous 20-yard drive to lift the sagging spirits of the home crowd as they began to suspect there could be a disaster in the offing

The ponytailed Frenchman landed his second strike in successive home games having failed to figure at all as a marksman previously since his £3.5million move from Monaco in the summer.

But Petit was also the best and cleverest player on the pitch as Wenger looked to him for their inspiration in the absence of Bergkamp's silky touch.

Arsenal, who have now been beaten only once in the last 28 games, set an all-time Premiership record by chalking up their ninth consecutive victory.

But in the end they had to revert to their familiar 1-0 mode after the carnival football of the last few weeks.

It could have been much worse. In the closing minutes of a game in which Derby had failed to mount a single shot on target they were almost presented with a point by the ravages of nervous tension.

Nigel Winterburn put his head to a monstrous long clearance by Derby keeper Mart Poom and deflected it past David Seaman to bounce inches wide of the post.

Then Seaman, virtually a spectator all night, hesitated almost fatally over a routine clearance from a back pass and nearly let substitute Deon Burton collect a gift inside the area.

The loud whistle from the 38,000 plus crowd accurately reflected Arsenal's anxiety at the end but really they should have wrapped it up easily against a poor Derby side who have now been beaten six times in their last eight games and seen a European place disappear over the horizon.

Nobody told them, however, about the script which should have dictated they were a mere stepping stone in Arsenal's quest for the top prize.

Smith team battled with a will and a pride which sometimes took them over the border of legality. Lee Carsley, stand in for injured captain Igor Stimac, was lucky that referee Neal Barry did not see his outrageous assault on Ray Parlour after he had already been booked for a foul on Nicola Anelka.

But Derby could have sworn referee Barry was on Arsenal's side when he gave them a spot kick in the 11th minute. It seemed no more than a stumble by big teenager Anelka when he went over Chris Powell's challenge inches from the dead ball-line

But Bergkamp amazingly let Derby off the hook, missing a penalty for the first time for Arsenal with a tame effort that allowed Poom a comfortable save diving to his left.

The omens looked bad for the Gunners at that stage, Ian Wright having missed a penalty at Derby earlier in the season when they suffered one of only four league defeats this season.

But Petit quickly lifted the mood of gloom with a magnificent goal. Anelka knocked the ball down on the edge of the box for Overmars and Rory Delap's sliding tackle took it away.

But Overmars, never renowned for his physical commitment, bit back with a toe in challenge that slipped the ball into Petit's path and the midfielder needed no more invitation to rocket home an unstoppable drive.

Arsenal should have had one or two more in a second half that almost became a non event. Derby could not muster anything of invention and, until the closing minutes of unexpected mayhem, it seemed just a matter of how many Arsenal would win by.

Petit powered a 25 yard free kick which came back off Poom but the big Estonian was alert enough in his recovery to stop substitute Chris Wreh stabbing home the rebound.

Poom distinguished himself again with a flying leap to claw away another blockbuster by Petit from even longer range and Overmars twice dallied over chances in the area when he seemed to want to walk the ball in.

But the final whistle was like music to Arsenal's ears and the bookmakers have now suspended betting against them singing a celebration tune when they meet relegation-haunted Everton with the title on the line at Highbury next Sunday.

Teams

Arsenal: Seaman, Dixon, Winterburn, Vieira, Adams, Anelka (Platt 82), Bergkamp (Wreh 30), Overmars, Keown, Parlour, Petit.

Subs Not Used: Bould, Manninger, Hughes.

Booked: Parlour.

Goals: Petit 34.

Derby: Poom, Rowett, C. Powell, D. Powell (Burton 74), Sturridge, Wanchope, Delap, Bohinen (Solis 82), Laursen, Carsley, Dailly.

Subs Not Used: Hoult, Van Der Laan, Kozluk.

Booked: Dailly, Wanchope, Sturridge, Delap, Carsley.

Att: 38,121

Ref: N S Barry (Scunthorpe).