Skipper Robin van Persie scored a hat-trick as Arsenal beat Chelsea 5-3 after twice coming from behind in a remarkable Premier League match of attacking brilliance and defensive mistakes at Stamford Bridge on Saturday.
The astonishing victory was Arsene Wenger's 500th since he became Arsenal manager in 1996, Arsenal's first away win in the league this season and Chelsea's first home defeat as the English top-flight continues to dish out goals galore.
Chelsea led through Frank Lampard after 14 minutes before Van Persie scored his first in the 36th minute and Chelsea skipper John Terry took advantage of some woeful Arsenal defending to put his side 2-1 up in the last minute of the first half.
Andre Santos struck Arsenal's second equaliser early in the second half before Theo Walcott scored a brilliant solo goal, picking himself up and continuing his run after slipping over, to give Arsenal a 3-2 lead after 55 minutes.
Juan Mata then equalised for Chelsea with a brilliant swerving shot, which Arsenal goalkeeper Wojciech Szczesny had no chance of saving, to make it 3-3 after 80 minutes.
Chelsea then committed suicide five minutes later with some more poor defending with Florent Malouda hitting a stray pass back to Terry, who stumbled to leave Van Persie to run in on Chelsea keeper Petr Cech and blast the ball into the gaping net.
The Dutchman then made it 28 goals from his last 27 Premier League games in this calendar year to make it 5-3 in the second minute of stoppage time with a swerving shot of his own to match Mata's.
Arsenal, who made a poor start to the season, climbed up to sixth place until the later matches at least and celebrated as if they had won a cup final.
Van Persie told Sky Sports: "You could see how happy we were at the end. We fought so hard for it, every single one of us -- it's a big, big win for us."
Wenger, whose team have been dismissed as title challengers following their poor start, said: "We needed to win with style and class and we did that against a big team and it was a big win for us.
"In the first half we looked fragile in defence, but less so in the second and kept going forwards and that made all the difference."
The result consigned Chelsea to a second successive defeat in a London derby after they lost at Queens Park Rangers last weekend and was the first time they had conceded five at home in a league match since Liverpool beat them 5-2 in the old first division in December 1989.
It was also the first time Arsenal had scored five against Chelsea since a 5-2 win over them in 1979 and Chelsea's stunned manager Andre Villas-Boas said: "It was so open it could have gone either way. We will have to reflect on the mistakes we made -- there are some things we must improve."