You obviously cannot boil down a north London derby to one tackle, but the GIF above was key, not only for the result but also for what it symbolised.
After Arsenal had initially dominated the early stages of the match, Spurs came back into it as their new players got a foothold in the game.
Nacer Chadli broke away and Per Mertesacker stepped in for the cleanest tackle you will likely ever see. A few transitions later and it was 1-0 to the Arsenal as Olivier Giroud swept home a Theo Walcott cross.
For 90 minutes, Mertesacker was immense. Shackling Roberto Soldado and winning header after header in one of his finest displays for the Gunners.
Meanwhile, Chadli was a big disappointment, firing over with a free-kick in Gareth Bale territory and generally failing to make his duel with Carl Jenkinson count.
One game does not make a season, but Per Mertesacker made sure north London was red on Sunday. And, Nacer Chadli knows all about it…