In pure geographic terms, Chelsea versus Tottenham Hotspur shouldn't be a particularly fervent rivalry; they're about 10 miles apart, a fair distance in a city boasting more than a dozen professional clubs. Indeed, if you were to walk from Stamford Bridge to White Hart Lane, you'd pass the Emirates about 6 miles into the journey.
But explaining London's football rivalries to the uninitiated is a complex task: It's not just about geography, but about history, status and a myriad of other factors. Tottenham hate Arsenal most, certainly, but Chelsea have rarely had particularly strong rivalries with West London neighbours like Queens Park Rangers, Fulham or Brentford, and so have directed their hatred northeast to Spurs.