Packers-Bears. Steelers-Browns. Cowboys vs. anybody in the NFC East.
Those are long-standing NFL rivalries.
Add to them 49ers-Seahawks, with a history of nastiness emanating from the college ranks for their coaches, and a hefty animosity built up in annual doubleheaders in their division. Now they meet for a spot in the Super Bowl.
Are those hard feelings for real?
"I think so, but it'll always be that way when you have two good teams in the same division," 49ers receiver Anquan Boldin said. "You play each other a couple times a year and if you're good enough, possibly three times a year. It was the same way when I was in Baltimore playing against Pittsburgh. You respect each other as foes, but there is really a dislike."
It's a healthy thing, really, because it makes for even more uncompromising action -- on the field and on the sideline.
One of these teams will emerge Sunday from ear-splitting CenturyLink Field headed for New Jersey to play for the sport's biggest prize. The other will carry into the offseason even more loathing for this opponent.
"There is no love lost; there is no love found," said Seahawks cornerback Richard Sherman, who will find himself lined up often against Boldin in the NFC championship game. "It's going to be intense. It's going to be physical. I don't know if there are going to be handshakes after this one."
That almost goes without saying with the coaches. When 49ers coach Jim Harbaugh was at Stanford -- where, incidentally, Sherman played after being recruited by current Seahawks coach Pete Carroll when he was at Southern California -- he ran up the score in a 2009 win at Los Angeles that prompted Carroll to ask him at game's end: "What's your deal."
Harbaugh's deal has always revolved around being a hard-edged player and coach. His teams embody that attitude, and it certainly has worked in San Francisco. The 49ers are 41-13-1 in his three seasons in charge, are in their third straight conference title game, and back down from no one.
That can make for some uncomfortable moments, whether it's Harbaugh's overzealous handshakes and back slaps after wins or his team playing up to (and sometimes beyond) the whistle.
Carroll claims the acrimony between them is overblown.
"For whatever reasons, you guys have had a field day with this," Carroll told reporters Thursday. "We have not been friends over the year, we just know each other through the games. We have a very confined relationship.
"I have great respect for Jim. That's it -- you guys have had a blast with it."
Carroll's Seahawks aren't exactly wallflowers, either. Defensively, at least, these are the NFL's two most physical and intimidating units.
That, in turn, can lead to ill will.
"I don't hate anybody," All-Pro cornerback Sherman said. "So I don't think (there's) hate. But passion, definitely. There will be some passion, some dislike -- some strong dislike. But there will be some intensity. It's playoff football.
"So even if we weren't two teams that are familiar with each other ... there's going to be a lot of intensity, a lot of chippiness, and a hard-fought game."
Where might this antipathy show most?
Try whenever Seahawks running back Marshawn Lynch -- his nickname, "Beast Mode," says it all about his style of play -- meets up with All-Pro NaVorro Bowman and his fellow linebackers, the best group in the NFL.
Or when Boldin, among the best clutch receivers in football, uses his physicality against Sherman, safety Earl Thomas, a fellow All-Pro, and the rest of the game's top secondary.
All of the matchups for Sunday are familiar to both sides, of course. And when division foes meet for the conference title -- each team won at home this season -- the results hardly are predictable.
Since the 1970 merger, there have been 15 third meetings in conference championships, 10 in the AFC, including the Seahawks losing to Oakland when Seattle was an AFC franchise in 1983. The 49ers beat the Rams in such a meeting in 1989. In 10 of those games, the host won.
What can be forecast for Sunday: hard feelings all around, even if 49ers linebacker Patrick Willis tones it down slightly.
"There's no question there's a lot of hostility between us," Willis said, "but at the end of the day they're another football team. So, there's always going to be dislikes. They're an opponent of ours and we want to win.
"If we weren't in this race right now there'd be no doubt that if they were playing against someone else, I would wish them well because it's in our division. But it's us playing, so there's not going to be any like at all there."