Mauricio Pochettino insists Arsenal were fresher than his Tottenham side because they were able to rest players in midweek before their north London derby win.
Arsenal came back from 2-1 down at half time to win a pulsating clash 4-2 on Super Sunday, having rested 10 players for the 3-0 Europa League win over Vorskla Poltava on Wednesday, while Spurs beat Inter 1-0 on Wednesday in an important Champions League clash.
Pochettino said Arsenal had a lot of energy, particularly when they went 3-2 up, and said it was very difficult to get back into the game from there on.
He told Sky Sports: "A very competitive game, tough for us because we were talking before that the fixture, after Chelsea and then Inter Milan, it didn't help with the fixture for us.
"But I think the team was very competitive, Arsenal was competitive with a lot of energy. The game was even until 2-2, when we conceded the third goal for the team it was so tough to come back, to try to be in the game.
"And then when you concede the fourth, and the sending off of Jan Vertonghen, of course the game was over.
"Of course the belief of the opponent, they were so fresh because eight, nine players didn't play on Thursday and they were preparing the game. It is not an excuse but when you concede 3-2 in the second half, you need energy to come back."
Juan Foyth's mistake with 15 minutes to go helped change the game, allowing Alexandre Lacazette to make it 3-2 to Arsenal, but Pochettino refused to blame the defender, and said he was among the better of Spurs' performers.
"I am a little bit disappointed with all the things that happen sometimes in football. Of course he failed in this action, but he was great in the game, he was fantastic during the game, and I am so happy.
"When you are young and you play this type of game, always it is difficult, but I think he was very good. I am not going to put the focus on him. I think the team were good up until 2-2, competing very well."
Asked about Jan Vertonghen's late sending off for a second yellow card, Pochettino can understand why the studs-up challenge on Lacazette looked rash in real time, but said on balance it was unlucky.
"I saw it, it is a little bit unlucky the action, because Jan touch the ball. It is normal, he is running, touched the ball and the action was dangerous. For me it was a little bit unlucky, but it looks bad live."