Match ends, Tottenham Hotspur 1, Arsenal 2.
Mathieu Flamini scored a superb volley to give Arsenal victory in their League Cup third-round tie at Tottenham.
Flamini slotted the visitors into the lead after Spurs keeper Michel Vorm could only parry an Alex Oxlade-Chamberlain shot back into his area.
Tottenham's Danny Rose had a penalty appeal rejected before the hosts equalised when Calum Chambers scored an own goal from Nacer Chadli's cross.
Midfielder Flamini then volleyed in from 20 yards to secure the win.
The France midfielder scored two goals in a game for the first time for Arsenal - and could not have picked a better opposition than their fierce north London rivals.
There had been speculation about how much of a role he would play this season having been overtaken by Francis Coquelin in the holding midfield role, and this was his first appearance of the campaign.
"I'm happy for the team and personally," he told Sky Sports. "I've heard many things in the press and I am still here. I don't have any problems with anyone at the club.
"It is never easy when you don't play every game. I had a point to prove."
Harry Kane remains without a goal for Spurs this season, though he did come close to scoring.
He had an opening in the first half when he controlled the ball on his chest eight yards out but took another touch instead of shooting and the chance was gone.
Kane later led a Spurs counter-attack but could only drag his effort wide from just outside the area,
The England striker did produce an acrobatic volley at the far post following an Andros Townsend corner, but the shot was cleared off the goalline by Kieran Gibbs.
League Cup fourth-round draw
Manchester City v Crystal Palace
Liverpool v Bournemouth
Manchester United v Middlesbrough
Everton v Norwich City
Southampton v Aston Villa
Sheffield Wednesday v Arsenal
Hull City v Leicester City
Stoke City v Chelsea
(Ties to be played on 27 and 28 October)
Tottenham manager Mauricio Pochettino: "It was a missed opportunity because we dominated the second half and had the better chances.
"We need to be happy in the way we played and disappointed with the way we lost the game. In general the performance was very good.
"Yes, we and our supporters will feel very bad, when you play against your sporting enemy you want to win more, but this is football."
Arsenal manager Arsene Wenger: "You do not expect Mathieu Flamini to score two goals but he was frustrated for a long time and he went for it.
"He is a fighter, Mathieu, and a winner as well. I told him at the start of the season it might be difficult for him to be a starter, but he decided to stay and fight.
"Overall we responded well mentally and physically to the challenge we faced and it was a convincing performance."
- 15DierSubstituted forN'Jieat 85'minutes
- 17TownsendSubstituted forSon Heung-Minat 67'minutes
- 22ChadliSubstituted forAlliat 75'minutesBooked at 76mins
- 7Son Heung-Min
- 2DebuchyBooked at 40mins
- 20FlaminiBooked at 37mins
- 8ArtetaBooked at 33mins
- 28CampbellSubstituted forSánchezat 67'minutes
- 15Oxlade-ChamberlainSubstituted forWalcottat 89'minutes
- Andre Marriner
- Shots on Target
Second Half ends, Tottenham Hotspur 1, Arsenal 2.
Attempt missed. Theo Walcott (Arsenal) right footed shot from outside the box misses to the left. Assisted by Aaron Ramsey following a fast break.
Attempt missed. Clinton N'Jie (Tottenham Hotspur) left footed shot from outside the box misses to the left.
Harry Kane (Tottenham Hotspur) wins a free kick in the attacking half.
Foul by Mathieu Flamini (Arsenal).
Foul by Christian Eriksen (Tottenham Hotspur).
Olivier Giroud (Arsenal) wins a free kick in the defensive half.
Substitution, Arsenal. Theo Walcott replaces Alex Oxlade-Chamberlain.
Attempt saved. Mathieu Debuchy (Arsenal) right footed shot from outside the box is saved in the centre of the goal. Assisted by Alex Oxlade-Chamberlain.
Attempt saved. Dele Alli (Tottenham Hotspur) right footed shot from outside the box is saved in the centre of the goal. Assisted by Harry Kane.
Kieran Trippier (Tottenham Hotspur) wins a free kick in the defensive half.
Foul by Alexis Sánchez (Arsenal).
Attempt missed. Clinton N'Jie (Tottenham Hotspur) header from the centre of the box misses to the left. Assisted by Christian Eriksen with a cross.
Substitution, Tottenham Hotspur. Clinton N'Jie replaces Eric Dier.
Attempt missed. Alex Oxlade-Chamberlain (Arsenal) right footed shot from outside the box is close, but misses to the left. Assisted by Aaron Ramsey.
Foul by Eric Dier (Tottenham Hotspur).
Olivier Giroud (Arsenal) wins a free kick in the attacking half.
Attempt blocked. Harry Kane (Tottenham Hotspur) right footed shot from outside the box is blocked. Assisted by Dele Alli.
Goal! Tottenham Hotspur 1, Arsenal 2. Mathieu Flamini (Arsenal) right footed shot from outside the box to the bottom right corner.