A new era of the most heated rivalry in German soccer got underway Saturday. A new American era, that is.

Fans of Borussia Dortmund and FC Schalke, who have watched their teams battle for decades, might not have realized it. But across the pond, Saturday was significant. For the first time, the derby featured two American teenagers – one on either side.

Christian Pulisic and Weston McKennie, both 19, were in the starting lineups for Dortmund and Schalke, respectively, for the first Revierderby of the 2017-18 season.

And they were on either side of a beatdown. Dortmund scored four goals in a span of 13 minutes in the first half to go up 4-0. Pulisic had a hand in the home side’s first. McKennie, on the other hand, picked up an early yellow card, and was one of two Schalke players subbed off after 32 minutes.

The two U.S. men’s national team midfielders are close friends. They met six years ago in U.S. youth national team camps, and now live roughly 30 minutes from each other in the northwest of Germany. They spent Thanksgiving together on Thursday.

Two days later, they were forced to become the fiercest of enemies, even if only for two hours. While Der Klassiker, Dortmund vs. Bayern Munich, has become the most well-known derby in the Bundesliga because of the two clubs’ recent success, Dortmund-Schalke is its most historic. It features more animosity.

And now it features two young American stars. Pulisic grew up in Hershey, Pennsylvania, and moved to Dortmund at age 16. He has been a fixture at Dortmund for over a year. He started his 50th Bundesliga match Saturday – the youngest non-German player to reach that benchmark.

McKennie grew up in Texas, and moved to Schalke at 18. He quickly progressed to the first team, and has broken into the starting lineup regularly this season.

They are the two brightest young stars in American soccer. And now they have a unique place in a special rivalry.

How long the Revierderby is Pulisic v McKennie is another question. Both have the potential to move to even bigger clubs in the future. But for now, the derby will double as the pinnacle of American soccer stars in Europe. It’ll be appointment viewing for American fans. And Saturday could be the first appointment of many.

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Henry Bushnell covers soccer – the U.S. national teams, the Premier League, and much, much more – for FC Yahoo and Yahoo Sports. Have a tip? Question? Comment? Email him at henrydbushnell@gmail.com or follow him on Twitter @HenryBushnell.