A touch of fortune went against us with both goals but we weren't at our best at the Emirates.
The game started in typical derby style, all hustle and bustle, few chances and Arsenal's goals actually came after our best spell.
Christian Eriksen hit the post and Harry Kane forced Petr Cech to save at full stretch just after the half-hour but 10 minutes later, we were 2-0 down.
The first goal came from a debated free-kick against Davinson Sanchez on Alexis Sanchez on 37 minutes. Mesut Ozil curled in the set-piece and Shkodran Mustafi headed across Hugo Lloris and home.
Five minutes later and we were facing an uphill task. Arsenal had got in a couple of times down our right and made no mistake at the third time of asking. Alexandre Lacazette broke clear and his cross to the near post was collected by Alexis Sanchez who fired into the roof of the net from the angle.
We dominated the second half in terms of possession without creating clear-cut opportunities. Kane had a sight of goal blocked by Nacho Monreal and Christian Eriksen fired over but Arsenal held firm and looked a danger on the break, Hugo Lloris forced into one-on-one saves to deny Sanchez.
A late flourish saw Eric Dier's header tipped away by Cech and Heung-Min Son volley over from 16 yards - it wasn't our day.
Mauricio Pochettino made five changes to the team that started against Crystal Palace before the international break. Lloris, Kieran Trippier, Ben Davies, Mousa Dembele and Dele Alli returned for Paulo Gazzaniga, Serge Aurier, Danny Rose, Harry Winks and Son. Michel Vorm also returned to the bench.
OPENING STAGES: FRANTIC START, FEW CHANCES - 1-30mins
As expected, the ball pinged around everywhere as both teams looked to get a foothold in the game. Kane had an early chance saved by Cech while Arsenal got away down the right twice and we cleared the danger.
WOODWORK: ERIKSEN HITS POST, CECH DENIES KANE - 33-34mins
Our best spell of the half culminated in two good chances. First up Davies, always a threat down the left, picked out Eriksen whose path to goal looked blocked, but he managed to drive a shot that hit the outside of the post. A minute later, Moussa Sissoko picked out Kane and Cech grabbed his looping header at full stretch.
GOAL: ARSENAL 1-0 SPURS - SHKODRAN MUSTAFI - 37mins
Davinson Sanchez looked harshly judged to have fouled Alexis Sanchez on the left, Ozil curled in the free-kick and Mustafi rose highest to plant a header home off the far post, opening the scoring.
Above: Jan Vertonghen tackles Hector Bellerin.
GOAL: ARSENAL 2-0 SPURS - ALEXIS SANCHEZ - 42mins
We'd seen danger twice down the right side and this time the Gunners made us pay. This time Lacazette got away and looked for Alexis Sanchez at the near post, the ball bobbled around before Sanchez fired into the roof of the net from the angle.
CHANCES: DIER AND SON CLOSE - 81-90+4mins
Dier cushioned a header across goal in the direction of Davinson Sanchez and Fernando Llorente - introduced along with Son as part of a double attacking change on 75 minutes - but Cech managed to claw the ball out from under the bar and away from danger. Moments later, Llorente won an important header and nodded down for Son in a pocket of space just inside the area but he could only blaze over. We continued to chase the game and after Lloris stood up well to deny Alexis Sanchez one-on-one, Son's good strike was well blocked by Mustafi in added time.
MAURICIO POCHETTINO SAID
"I’m disappointed because the effort was massive and we lose the game. The small details changed the way we played in the game but we need to keep going, look forward and try to be ready for the next game. For me, that action (the first goal) changed the game, 1-0 down and then we conceded the second goal quickly (after that) and that was a key moment for the team."
HUGO LLORIS SAID
"I’m not disappointed with the spirit of the team because the spirit was great. We showed character and even at 2-0 down we kept playing, kept fighting and kept face. We missed something in the last third and the two goals... that’s football and it can happen. The goals were a big impact in a game of this level. It was so tight between both teams with a lot of quality. We need to switch off from this game and try to bounce back at Dortmund."
Arsenal (3-4-2-1): Cech, Koscielny (c), Mustafi, Monreal, Bellerin, Ramsey, Xhaka, Kolasinac, Ozil (Iwobi 84), Sanchez, Lacazette (Coquelin 73). Substitutes (not used): Ospina, Mertesacker, Maitland-Niles, Wilshere, Welbeck.
Spurs (3-4-2-1): Lloris (c), Dier, Sanchez, Vertonghen, Trippier, Dembele (Winks 62), Sissoko, Davies, Eriksen, Dele (Son 75), Kane (Llorente 75). Substitutes (not used): Vorm, Aurier, Foyth, Walker-Peters.
Goals: Arsenal - Mustafi 37, Sanchez 42.
Yellow cards: Arsenal - Xhaka 32, Sanchez 38, Mustafi 48, Monreal 73; Spurs - Kane 50.
Referee: Mike Dean.
Attentions quickly turn to the Champions League and the return fixture against Borussia Dortmund on Tuesday, kick-off 7.45pm (UK time). Already qualified for the knockout stages of the competition, we'll be looking to complete the double against the Germans after a 3-1 triumph at Wembley on matchday one.