Champions Chelsea broke Arsenal's 10-year unbeaten league streak against their west London rivals on Sunday as Didier Drogba's fluke second-half goal gave them a 1-0 victory at Stamford Bridge.
It was Drogba's third goal this season against the Premier League runners-up after the two he put away in the season-opening Community Shield in Cardiff a fortnight ago.
The 73rd-minute strike also spoiled Arsenal manager Arsene Wenger's celebration of 500 matches in charge at Highbury.
Until the goal the match had been a dour affair between the two English heavyweights, neither side looking sharp in the warm early season sunshine.
It improved in the second half after Chelsea manager Jose Mourinho had brought on some 70 million pounds ($126.3 million) worth of substitutes.
Last year's recruit Drogba replaced ineffective Hernan Crespo, record $47 million dollar Ghana midfielder Michael Essien made his debut coming on for Eidur Gudjohnsen and winger Shaun Wright-Phillips, captured from Manchester City, substituted Arjen Robben.
The game was settled when last year's footballer of the year Frank Lampard curled a free kick into the box from the right and the ball bounced off the on-rushing Drogba's knee and crept inside Jens Lehmann's near post.
"It was a defensive mistake," Arsenal manager Arsene Wenger told SkySports. "If you allow an opponent into a position to get lucky it's a defensive mistake.
"We had a lot of possession but we were not incisive enough. We had four chances to score and that should be enough to win a game like this."
Drogba could have rubbed salt into Arsenal's wounds in the dying seconds of the match when Lampard again sent him free but he lobbed tamely into the arms of Lehmann.
Arsenal's passing had looked slicker before the break, although they lacked any cutting edge and rarely threatened a Chelsea defence marshalled by immaculate skipper John Terry.
BEST CHANCE
Their best chance came in the 77th minute when Thierry Henry forced Petr Cech to tip the ball wide of the Chelsea goal. The France striker also wasted two earlier opportunities when the score was still deadlocked.
Chelsea, the favourites to retain their crown, held out easily for their 39th consecutive match undefeated at home to join Tottenham Hotspur, Manchester United and Charlton Athletic at the top on six points.
"It's a fantastic victory, two matches, six points," said Mourinho who could find no place in the squad for England midfielder Joe Cole.
"We have beaten our direct opponent for the league...psychologically it's important because we haven't beaten them in the league for a long time.
Earlier in the day Everton, who finished fourth last season, picked up their first points of the new campaign with a 1-0 victory at Bolton Wanderers thanks to a second half goal from Marcus Bent.