It’s Milwaukee versus Denver in what some are calling the #BeerSeries. And there’s a lot of beer on the line.

The professional baseball teams from each city are squaring off over the next week in a best-of-five playoff series that pits the home of Miller Brewing Company against the home of Coors Brewing Company — and the nation’s No. 2-selling beer against the No. 3.

Both breweries are all-in for their local teams, with each holding naming rights for their respective stadiums: The baseball stadium in Milwaukee is named Miller Park, while the stadium in Denver is Coors Field.

Both also are owned by MillerCoors, sparking an intercompany rivalry between the brewers in Golden, Colo., and their counterparts in Milwaukee. And each brewery is standing behind its home team with a friendly wager: Free beer for the winning city.

On Friday, Oct. 12, fans of the winning team will be able to get a free beer at participating bars across the winning city. The losing team’s hometown brewery will pick up the tab.

“While Miller Brewing and Coors Brewing work together to provide great beer to fans everywhere, there’s nothing wrong with a friendly rivalry, especially when the fans are the true winners,” says Adam Dettman, director of brand experience for MillerCoors.

Both cities have rich brewing histories that stretch back into the 19th Century.

Milwaukee’s Miller Brewery, which opened in 1855, is among the oldest operational breweries in the country, spanning 80 buildings on 82 acres on the city’s west side. It employs more than 600 workers.

Coors Brewing, meanwhile, opened in 1873 in Golden, Colo., a Rocky Mountain outpost just west of Denver. It boasts the largest single-site brewery in the United States and employs nearly 900, while an attached malting plant, can-making plant and bottlemaker combine to employ more than 1,000 others.

“Coors Field and Miller Park are our namesake stadiums in our brewery hometowns, which makes this series even more exciting,” Dettman says. “These are two great clubs, and they’ve got a rivalry that extends all the way through to our employees. This is a great chance for us to celebrate with them and our fans in both cities.”