Sagna was thrilled with the display, and believes the victory could have real significance on the rest of the season.
"It's very important," he told arsenal.com. "We want to stick to the top. From now on, we just need to keep focused, look forward and win game by game.
"It was amazing to play. It's always a great pleasure to play [in] a derby, especially when you win. It's just great. We managed to score many goals."