By almost every measure, the National Football League is the most popular sports league in the United States. And as the NFL continues to grow at an unprecedented rate both in terms of viewers and profit, the story lines have become endless and the rivalries are enormous.

Not many people have a better handle on the league's status than Fox's Joe Buck. The 43-year-old Buck has been Fox's lead play-by-play man for one decade, and in that span he's called three Super Bowls and countless playoff classics. This week Buck said he can't remember a season with more anticipation than 2012.

"I assume at some point [the league's popularity] will level off," Buck says. "But until it does, for us at Fox, the guys at CBS, the guys at NBC, the guys at ESPN, you just ride that wave and you smile every time the ratings come out because they’re just unbelievable, blow-you-away numbers. The popularity is at an all-time high, and we’re lucky to get to cover it."

Buck, who does NFC games as part of the conference's deal with Fox, says the NFC East might have the best top-to-bottom rivalries. While there's no singular rivalry that stands out above the rest, all together it's difficult for any division to top the depth of the NFC East.

"It’s to our advantage that at Fox we cover the NFC," Buck said. "And if you want to say Cowboys-Giants, you want to say Eagles-Giants or throw the Redskins in there now with RGIII and the game they just had last weekend against New York. There’s a lot to like there."

With the popularity and passion surrounding the league these days, it doesn't take long for new rivalries to develop. In that regard, no team is gaining steam as quickly as the San Francisco 49ers. In additional to a geographical rivalry with the Oakland Raiders, the 49ers appear to be reviving a once-great matchup with the New York Giants.

Plus, having a coach like Jim Harbaugh never hurts.

"Whoever [the 49ers] play," Buck added, "with the intensity of Harbaugh you have the makings for fireworks every time they line up for the opening kickoff."

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