Pennsylvania-based Yuengling Lager hit the Bay State with a bang back in March. Today it’s in the fight of its life to win over Boston beer drinkers.

“I’m not going to sugarcoat that it’s been a very competitive market, more competitive than any market we’ve seen before,” said Yuengling chief operating officer David Casinelli, a beer industry legend who turned a stale regional brand into a fast-growing powerhouse.

Yuengling today is the largest domestically owned brewery, as well as the nation’s oldest brewery. But Boston has proven a tougher keg to tap than many anticipated.

“(Yuengling) was hot out of the gates and hit a wall fast,” said Matt Mooney, the beer buyer at Boston Beer Garden in South Boston. “We sold three kegs of it the first Monday alone. Before long we were down to one keg a week.”

Boston Beer Garden recently kicked Yuengling off its draft list in favor of faster-selling brands.

“The novelty has worn off,” said Adam Hawk, manager at the Baseball Tavern in Fenway. Retailers report similar stories.

Yuengling faces three unique challenges in Boston.

First, New Englanders are largely suspicious of outside brands and prefer to support our own.

Call it Krispy Kreme Syndrome. The famous doughnut maker arrived in Boston a decade ago amid a wave of hype but fizzled badly, as local consumers stayed true to the likes of Dunkin’ Donuts.

“Most of our customers have remained loyal to their favorite brands,” said Josh Durant, the manager at Supreme Liquors in Quincy.

The second challenge is Boston’s mature and sophisticated market of beer consumers. It’s the only city in America that’s home to two of the nation’s largest craft breweries, Samuel Adams and Harpoon.

Massachusetts boasts about 90 other breweries, many vying for space in local barrooms and retailers.

Finally, the Boston beer business is a rough-and-tumble arena ruled by distributors who play hardball. They’re not afraid to influence pub owners to dump rival brands.

One local distributor reported knocking 22 Yuengling taps out of local bars last week alone, while one salesmen hangs the Yuengling taps pubs have dumped in favor of his brands on the wall of his office like trophies.

“We’re big boys,” said Casinelli. “We live in a competitive world, and we’re completely fine with that. I guess when Yuengling comes to market we bring out the best and worst of everyone, because there is fear that we have the potential to become a very big brand in that market.”