Since 1999, MillerCoors has brewed several of Pabst’s brands, including Pabst Blue Ribbon, Old Milwaukee, Lone Star, and National Bohemian (known to its fans as Natty Boh). With the agreement between the two companies set to expire in 2020, tensions have been spilling over, NBC News reports.

MillerCoors claims it has less brewing capacity and that Pabst doesn’t pay enough for the service, the Detroit News reports.

NBC reports that in 2016, MillerCoors closed its North Carolina brewing facility that produced 8.8 million barrels of beer and that the company had previously said it may have to close a California facility that has a capacity of 6 million barrels per year.

Pabst, on the other hand, argues that the company is just trying to drive them out as competition as a response to MillerCoors’ declining sales, NBC reports. Lawyers for Pabst argued that MillerCoors produces, packages, and ships nearly all of Pabsts’ products, according to the Detroit News.

In the case, which was first filed in 2016, Pabst seeks more than $400 million in damages and asks that MillerCoors help them find a solution, according to NBC News.

“Even though MillerCoors’ market power is much larger than Pabst’s, we will not allow this industry bully to push us around,” Pabst said in a statement. “We are confident that the court will see MillerCoors’ fabricated ‘capacity’ concerns for what they are: a thinly veiled, bad faith attempt to unlawfully hurt a competitor.”

The beer giants are set to go to trial, with a jury hearing arguments beginning on Tuesday. The trial is expected to last until Nov. 30.