When you think of great rivalries in world football what do you think of?

Do you think AC Milan and Inter fighting it out at the San Siro? How about Manchester United going for Liverpool's throat at Old Trafford? Or perhaps you're Spanish and you think of Barcelona and Real Madrid fighting for dominance at the Camp Nou?

Starting this week, I will be taking a look at the great rivalries of world football. This week, I start off in Buenos Aires, Argentina, where you can find Boca Juniors and River Plate fighting it out in the Superclásico.

The rivalry between River Plate and Boca Juniors is perhaps the greatest and fiercest rivalry in the world. Starting in 1913, with a 2-1 River Plate victory, the two cross-city rivals have met over 160 times. Of those meetings, Boca have won the majority of the matches. The latest match, in May of this year, saw Boca defeat River, 1-0.

Buenos Aires has the largest concentration of football clubs in the world. However, the two most famous ones in the city and Argentina are Boca Juniors and River Plate. The two clubs are only 7km away from each other and it's estimated that 73 percent of the Argentine population are either a River Plate of Boca Junior fan. While the two clubs share the same city, they could not be more opposite.

Club Atlético River Plate was founded in 1901 and since then, has been known as the club of the upper-middle class. In fact, their official nickname for fans is Los Millonarios (The Millionaires). However, Boca fans prefer to call them Las Gallinas (Chickens) because they are scared to beat win. This nickname started in 1966, when River had a 2-0 lead against Uruguayan team Peñarol, but they ended up losing the match, 4-2. They've won a combined total of 38 official tournaments.

Club Atlético Boca Juniors was founded in 1905, and has been known as the club for the working class. Their official nickname is Los Xeneizes (The Geonese after the Geonese Italians that founded the club). River Plate fans call them, Bosteros (Manure Handler) because they are a club for poor people. Boca have not been as successful regionally, but they have won 18 international titles, the same number as European giants, AC Milan.

What makes this rivlary so special though? In 2004, the English newspaper, The Observer, named the Boca-River derby number one on the top 50 sporting things to do. When you see a match on TV or go to the actual match, you will always see fans passionate about their teams. If you ever go to a match you can feel the energy in the stadium. You'll see fireworks, confetti, flags, banners, and paper. You'll hear songs, you'll hear yelling, you'll hear cheers, you'll hear groans.

To many fans and players in Argentina, it's not just another derby. It's a symbolic battle between the rich and poor. The hierarchy and the lower class. It's River Plate against Boca Juniors. Many say that Latin America has some of the most passionate football fans in the world. Take a look at Boca-River derbies, and you can't help but agree.

For those of you interested in that list of top 50 things by The Observer, here's the link. There's some very interesting things there.