Chelsea host the Gunners after their impressive midweek Champions League win against Barcelona.
"It’s a London derby," Fofana said. "Every time, it’s a difficult game.
"It's a little bit similar to the Barcelona game. We need to defend 11 versus 11, all together, and try to do everything for the clean sheet. We need to stay together and stay solid. It's good to keep a clean sheet, but we will also need to score and attack – and everyone needs to attack as well. We work well as a team, which is very important.
"The key is just working every day, trying to improve everything and staying together because not every day is easy and very good, so we just need to stay together as a team.
"For sure, we know if we win, the points gap is a little bit closer, but the season is long.
"For sure, we want to win the game because it's a London derby, and when you win against Arsenal, that success feels a bit better. Everyone is focused on that. The most important thing is just to work and progress. We're only in November, and we need to continue to work until the end of the season."