Listen to live commentary on BBC Radio 5 Sports Extra and the BBC Sport website every Sunday, with San Francisco 49ers v Philadelphia Eagles this Sunday (from 21:00 GMT)
It’s a heavyweight match-up that has been mentioned in the same breath as Rocky Balboa versus Apollo Creed.

Over the last two seasons, the Philadelphia Eagles and San Francisco 49ers have not only been two of the NFL’s best teams, they have become the league’s newest rivals.

It began with last season’s NFC Championship game, when the Eagles beat the 49ers before losing a Super Bowl classic to the Kansas City Chiefs.

San Francisco felt hard done by, and there has been plenty of trash talk since, but they have the chance to set the record straight when they visit Philly this Sunday, in week 13 of the regular season.

The “exciting” 49ers and “unstoppable” Eagles are currently the top two seeds in the NFC Conference so could meet again in January for a spot in Super Bowl 58.

And given both have the potential to become NFL dynasties, their rivalry could soon match that of Philadelphia’s favourite fictional fighting son and his famous foe.

From decimated to a dynasty?
San Francisco seem destined to win another championship after rebuilding a roster that former 49ers player Joe Staley says was “pretty much decimated” in 2017, when John Lynch was appointed general manager and Kyle Shanahan head coach.

Via shrewd draft picks and free agent signings, they have turned the five-time Super Bowl winners back into genuine contenders, reaching three of the last four NFC Championship games and losing to the Chiefs in Super Bowl 54.

And in their quest to bring the Lombardi Trophy back to the Bay for the first time since 1995, the 49ers took their roster to another level with mid-season trades for free-scoring running back Christian McCaffrey last year then defensive end Chase Young last month.

“This is the culmination of a lot of hard work in the front office and on the coaching staff,” Staley told BBC Sport. “They built it the right way, and myself, a lot of former players and fans take a lot of pride in that.

“This has been a vision of having sustained success for the franchise, not just a one or two-year window, so it’s really exciting that it’s not only going to be this season but for years to come.

“The way the roster’s been built, especially at key positions, this team has so much talent – offensively and defensively. The opposition has to play their absolute best to even have a chance.”

Meanwhile, a squad with similar talent and depth has been built in Philadelphia, the city of brotherly love. The Eagles have also developed a play some feel should be outlawed as it resembles a rugby scrum.

The ‘tush push’ is a variation of a quarterback sneak, where the QB aims to burrow through the line of scrimmage to gain the yard or two needed for a touchdown or first down.

Also named the ‘brotherly shove’ in homage to Philadelphia’s mastery of the play, it involves team-mates lining up to push the quarterback forward.

It looks easy, and other teams have tried to copy it. But no-one can run it as well as the Eagles. Two New York Giants players were even injured on a failed attempt in October.

Speaking on BBC Radio 5 Live, former NFL defensive end Jack Crawford joked: “I’m glad I don’t play any more because of that play! It needs to be banned immediately because [quarterback] Jalen Hurts is too strong – he can squat 600lb! Now you’ve got people pushing him from behind. You can’t stop it.”

The play helped Hurts set the record for most rushing touchdowns by a quarterback in a season (18), including a record three in the Super Bowl.

San Francisco players have been asked all week about how to stop it. Perhaps linebacker Fred Warner has the answer, having jumped over the line of scrimmage to tackle the quarterback when the Minnesota Vikings tried a tush push in October.

The play continues to divide opinion and the NFL will consider banning it in the off-season, but that decision will be based on injury data, not how many critics call it “boring”.

Last season’s NFC Championship game became a one-sided affair after San Francisco suffered injuries to both their quarterbacks, which led to “a lot of boo-hoos” from the 49ers, said Eagles linebacker Haason Reddick.

Some San Francisco players claim they have the better team, yet Philadelphia have the NFL’s best record of 10-1 having bounced back from their loss to the New York Jets by grinding out wins over four of the league’s top teams – Miami, Dallas, Kansas City and Buffalo.

The 49ers are now 8-3 having regrouped after three straight defeats in October. Even coach Shanahan said “it is random” that they are rated as marginal favourites for the trip to Philly, while Eagles coach Nick Sirianni said: “I think it’s OK to be the underdog.”

Sirianni added: “Before I set foot in Philadelphia all I knew about this city was Rocky versus Apollo Creed. The city plays the underdog well.”

The Eagles certainly have done just that in recent history; their players even wore dog masks during their unexpected run to the team’s solitary Super Bowl win, which came in February 2018. Will Philly soon be celebrating a third Super Bowl appearance in seven years?

“This is going to be such a good game. I think whoever wins will make it to the Super Bowl,” NFL pundit Phoebe Schecter said on BBC Radio 5 Live.

“Both teams haven’t been at their greatest but they’re finding a way to win. But it’s the Eagles for me, because they can attack you in so many different ways.”

Crawford added: “In the trenches, their offensive and defensive lines are the best in the league. I have to go with the Eagles, they’re just too strong in every position group.”