The 27-year-old signed for the Gunners from Werder Bremen over the summer and he admits that there is nothing like it in the Bundesliga.
"This is my first special game for Arsenal," said Mertesacker. "A lot of people have been telling me about it, how massive it is, and what a special experience it is and I am looking forward to it.
"It is an especially important game for Arsenal and for me. There is nothing similar to it in Germany.
"You cannot compare Bremen against Hamburg because they are not quite in the same city, so the London derby is bigger."
Arsene Wenger's side go into the match in 13th place in the Premier League, while Spurs occupy sixth.