Arsenal struck first blood in the North London Derby at the Emirates thanks to Shkodran Mustafi who capitalised thanks to a very soft free-kick being awarded to the Gunners.
Referee Mike Dean gave the home side an free-kick outside the Spurs area after he thought Spurs Davinson Sánchez pulled down Alexis Sanchez.
Upon review it seemed Dean got the decision wrong and Sanchez had in fact made a perfectly good challenge against the Chilean.
Fortunately for Arsené Wenger the free was awarded and Mustafi capitalised with a header in the 36th minute.
Arsenal double their lead not long after thanks to a tap in from Sanchez from on the line in the 41st minute.