To much acclaim, ESPN's NFL Nation established earlier this week the top rival for each of the league's 32 teams. Now it's time to look closer at the root of those rivalries: the juicy interpersonal enmities; jealousies; and (occasionally) contrived personality competitions among players, coaches and administrators.

In other words: Let's get it on!

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You could argue that Burfict ended the Steelers' Super Bowl hopes last season. His tackling led to injuries for running back Le'Veon Bell (knee), quarterback Ben Roethlisberger (shoulder) and receiver Antonio Brown (concussion) -- the last of which contributed to a three-game suspension for Burfict to start the 2016 season. Burfict's Twitter war with Steelers running back DeAngelo Williams this offseason has fueled the rivalry, and this one appears rooted more in genuine dislike than in gamesmanship. Burfict's playing style implies little regard for the well-being of other players, who have noticed and are fighting back.

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Norman has every skill you could want in an elite cornerback, and that list includes an innate ability to unnerve opposing receivers. Norman and the Carolina Panthers whipped Beckham into a frenzy during last season's Week 15 matchup with the New York Giants. Beckham dropped all pretense of competition and fought Norman throughout the game, leveled a series of cheap shots and in the end fell short of a 100-yard game for the first time in seven games. Although Norman was hardly blameless, he avoided suspension. (He was fined $26,044 for two illegal hits, however.) Beckham was not so lucky and sat out Week 16. He has had a full offseason to work on his self-control, and he will need it; Norman has signed with the NFC East rival Washington Redskins and thus is scheduled to face Beckham and the Giants twice each season.

• ESPN's Dan Graziano writes the Beckham-Norman rivalry is the most intense one in the NFL.

3. James Harrison vs. Roger Goodell

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The NFL commissioner has targeted the Steelers linebacker for years to reduce dangerous contact in the game, fining him at least $150,000 for illegal hits. Harrison has responded with public invective and disrespect at every turn, including a 2011 interview with Men's Journal in which he referred to Goodell as a "crook" and a "devil" and was quoted as saying: "If that man was on fire and I had to piss to put him out, I wouldn't do it. I hate him and will never respect him." On Twitter, he has taunted Goodell about the league's botched investigation into Ray Rice's domestic abuse case. Most recently, Harrison said he would submit to an NFL interview on alleged use of performance-enhancing drugs only if Goodell himself traveled to his house. This rivalry might be one-sided, but it's not just for show.

4. Ryan Grigson vs. New England Patriots

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The Patriots and their fans have plenty of targets for their enmity -- including one they share in common with James Harrison -- but for now let's celebrate their disdain for the Indianapolis Colts' general manager. It was Grigson, of course, who first alerted the NFL about football inflation before the 2014 AFC Championship Game via an email to the league office. And it was Grigson who complained to NFL officials on site during the game. The NFL backed Grigson via the Wells report, but he is more or less the patient zero of Deflategate: It spread from him.

5. Brock Osweiler vs. John Elway

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Although he never said so publicly, Osweiler walked the path of a man who felt scorned by the team that drafted him in 2012 and (briefly) made him its starter last season. The Denver Broncos were 5-2 in Osweiler's seven starts during their run leading up to the playoffs, but Peyton Manning replaced him when the postseason began. If that didn't engender Osweiler's contempt, perhaps it was Elway's measured financial offer as free agency approached. Elway's ambivalence on Osweiler's long-term impact seemed clear. Regardless, Osweiler bolted for the Houston Texans in the earliest moments of free agency and has since skipped the Broncos' trip to the White House and their Super Bowl ring ceremony. Next stop: Monday Night Football in Week 7 on ESPN, when the Broncos and Texans will square off in Denver.

6. Cam Newton vs. Ed Hochuli

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Newton accused Hochuli last season of a serious offense, and he didn't back down when the NFL backed Hochuli's denial. After taking a hit outside of the pocket in a Week 3 game between the Panthers and the New Orleans Saints, Newton asked Hochuli -- the game's referee -- to explain why he did not call a roughing penalty. Newton later told reporters that Hochuli said: "You're not old enough to get that call." Broadcast replays showed the two men talking after the play, but no audio was available. The NFL accepted Hochuli's explanation that his words were in fact: "The difference is you were running." Hochuli denied any favoritism or reference to Newton's age. As with any sport, referees have long memories, and Hochuli isn't likely to forget that Newton questioned his integrity in public.

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Sherman, the lively Seattle Seahawks cornerback, has provoked "feuds" with players throughout his career. Quotation marks are necessary because Sherman, by all accounts, is more showman than hater. He has a good time with it, even if his targets do not, and I would have to imagine it dug at no one more than the Patriots quarterback after the Seahawks' 24-23 victory over New England in 2012. As Brady walked off the field, jaw clenched and eyes locked on the ground, Sherman peppered him with his "You mad, bro?" line. Brady said afterward that he didn't hear Sherman, but his body language suggested otherwise. Brady added: "My dad taught me at a young age to play with class and respect and give my opponents respect, and certainly I have a lot of respect for the Seahawks." Yup.

• ESPN's Sheil Kapadia writes Sherman has been the king of player rivalries.

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Two and a half seasons have passed since Smith implored Talib to "ice up, son," yet it still seems like yesterday. Smith and Talib battled throughout the Panthers' 24-20 victory over the Patriots in Week 11 of the 2013 season, scuffling twice after the whistle. Talib left early because of a hip injury, leading to Smith's rehab advice. Smith later wore a shirt with the slogan, but alas, the two are not scheduled to play against each other this season. (Smith is now with the Baltimore Ravens, and Talib is a member of the Broncos.)

9. Johnny Hekker vs. multiple teams

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Hekker might appear to be a mild-mannered specialist, but the Los Angeles Rams punter has enraged the Ravens and the Seahawks with cheap shots after punts. (He also entertained viral video producers by cowering in the face of retaliation -- always a good look.) When the Ravens saw replays of Hekker hitting Cliff Avril from behind, then running away from him and later Seahawks defensive lineman Michael Bennett, they reminded the world via Twitter that a similar incident had taken place in a Rams-Ravens game earlier in 2015. In a way, Hekker proved his intelligence: The only time a punter should hit someone is in an emergency or by surprise. When someone gets mad at you, you get down and stay there. Hekker apologized for his hit on Avril, but what's done is done.

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Don't make Gronk mad. Brown -- currently a free agent -- found that out the hard way in 2014, when, according to Gronkowski, he spent most of a game between the Patriots and Colts "yappin' at me." So during a Jonas Gray touchdown run, Gronkowski drove Brown far out of bounds on a block, then slammed him to the ground. Gronkowski happily took a penalty for the play and delivered an explanation for the ages afterward: "I took him and threw him out of the club. I was the bouncer, picked him up and tossed him out of the club on that one touchdown. So that was perfect." Yes, Gronk. Yes, it was.