The power and fury of a raw, spiteful London derby exploded in a stoppage-time climax as Emmanuel Petit grabbed a dramatic last-gasp goal.

The result extends Arsenal's winning run to 11 and keeps them on course for a place in next season's Champions League but left West Ham roaring with bitter indignation.

The Hammers insisted the pony-tailed Frenchman, an early second-half arrival from the substitutes' bench, had handled Dennis Bergkamp's throw-in before blasting a 20-yard rocket that deflected viciously beyond their 18-year-old fourth-choice goalkeeper Stephen Bywater making his full Premiership debut.

Paolo di Canio and Trevor Sinclair complained furiously to referee Paul Durkin but only incurred more bookings for West Ham in a contest that always teetered on the edge of outright antipathy.

And in the third minute of injury time, with Arsenal milking the applause of a comeback victory that had long seemed likely to elude them, Sinclair took away Ray Parlour's legs and was shown the inevitable red card.

At the end of a breathless, sometimes brawling confrontation, West Ham manager Harry Redknapp had to race onto the field to restrain Marc-Vivien Foe and Paulo Wanchope jostling the referee.

West Ham, their forces decimated by a plague of injuries and illness, had fought like tigers to take a surprise lead through Di Canio five minutes from half time.

And they were hanging onto their advantage when Kanu knifed them open with a through ball that put in the quicksilver Marc Overmars to fire in a long-overdue equaliser.

But renewed equality only added extra tension to an already heated battleground, familiar territory for these two rivals.

Only last October Arsenal's Patrick Vieira was sent off at Upton Park and later banned for six matches after spitting at Neil Ruddock and tangling with a police officer in the tunnel.

Hammers' Italian idol Di Canio, who suffered the two fouls that led to Vieira's marching orders that day, went through his full range of histrionics in this seamy sequel. And at the end both protagonists found themselves in the book again.

There will probably be recriminations at the Football Association following the unsightly proceedings after the final whistle but what mattered most to Arsenal was the win that took them three points ahead of Liverpool with a game in hand in second place.

West Ham's arrival at Highbury brought a new depth of meaning to their manager Harry Redknapp's familiar injury-crisis phrase "down to the bare bones."

They were, indeed, with no fewer than 13 players unavailable through either injury or illness including Frank Lampard, Joe Cole and Stuart Pearce all out for the season along with goalkeeper Shaka Hislop.

And although the starting line-up still boasted such luminaries as Di Canio, Igor Stimac and their latest talent, the French striker Frederic Kanoute, their substitutes bench was studded with unfamiliar young faces like Grant McCann, Terrell Forbes and former Arsenal reserve Omer Riza alongside 42-year old goalkeeping coach Les Sealey.

Yet West Ham started and finished the first half with a splendid flourish, the lively Kanoute thundering a snap shot at David Seaman after the rubber-limbed Wanchope wreaked penalty area havoc in only the fourth minute.

And after Arsenal had virtually set up camp in the Hammers half, Di Canio's precise strike produced a shock 40th minute lead.

Lee Dixon tripped trying to deal with Sinclair's determined run out on the left and the former England Under 21 international coolly pressed on into the area to unleash a cross-shot which Seaman could only parry out to Canio who steered his shot past Silvinho on the line.

West Ham had incurred three bookings in a four-minute spell to interrupt Arsenal's almost constant attacking probes.

Inevitably, a fair percentage of the Gunners' bayonets got through - but rarely as far as young Bywater, who leaked four goals against Bradford City when coming on as a substitute in his Premiership bow earlier this season but looked brave and assured here.

Marc Keller cleared off the line to tidy up his own mistake which allowed Dennis Bergkamp to lob the rookie keeper after a precise Tony Adams header from an Overmars cross was deflected off a wall of defenders and over the bar.

Slick inter-play between Kanu, Bergkamp and Overmars following a Dixon free-kick ended with a combination of Bywater and Moncur thwarting Overmars inside the six-yard box.

But though Bergkamp grazed the outside of a post, trying to curl in an equaliser and Arsenal had a good shout for a penalty turned down when Foe handled Parlour's cross, it was Arsene Wenger's team who went in at the interval with a bloody nose after di Canio's latest strike against them.

The big question at the start of the second half was would West Ham buckle to the inevitable pressure like they did in the 7-1 crash at Manchester United after taking a shock lead.

But Bywater fell on Bergkamp's crisp low drive in the first minute after the break and it strengthened the Iron resolve sufficiently to spring counter attacks in which Wanchope spurned a pair of plausible opportunities, first shooting and then heading off target before Adams tried to get to him.

Overmars stumbled over a close-range chance with the goal gaping in front of him after Bergkamp wrestled off the limpet-like Foe to drag the ball back from the byline and Arsenal must have wondered where a goal was coming from.

Overmars soon supplied the answer. Put through by Kanu's lancing pass, the little Dutchman burnt off Foe with searing pace and although it seemed he had dallied too long over the shot, allowing the big Cameroon defender to get back at him, he eventually slotted it past Bywater.

Two minutes later the keeper stretched admirably to prevent Overmars doubling his money from the edge of the box.

But Arsenal would not be denied and the luck bounced their way at last when Petit's controversial winner pin-balled home.

Teams:

Arsenal: Seaman, Dixon (Petit 56), Adams, Luzhny, Silvinho, Parlour, Vieira, Grimandi, Overmars, Bergkamp, Kanu.

Subs Not Used: Winterburn, Manninger, Malz, Gray.

Booked: Luzhny, Vieira.

Goals: Overmars 69, Petit 90.

West Ham: Bywater, Potts, Stimac, Keller, Sinclair, Kanoute, Foe, Moncur, Carrick, Wanchope, Di Canio.

Subs Not Used: Sealey, Riza, Forbes, A. Newton, McCann.

Sent Off: Sinclair (90).

Booked: Foe, Stimac, Keller, Moncur, Wanchope, Sinclair, Di Canio.

Goals: Di Canio 40.

Att: 38,093

Ref: P Durkin (Dorset).