Pfizer on Monday said it filed a second lawsuit against Novo Nordisk and Meseraalleging that the Danish drugmaker’s attempt to outbid Pfizer to acquire the obesity biotech is anticompetitive.

Pfizer alleges that Ozempic maker Novo Nordisk’s proposed acquisition of Metsera would help it maintain its dominant position in the blockbuster obesity market by eliminating a smaller potential competitor, according to the lawsuit filed Monday in the U.S. District Court in Delaware. The suit also alleges that Metsera’s controlling shareholders conspired with the obesity biotech and Novo Nordisk.

Novo Nordisk did not immediately respond to a request for comment.

In a statementMetsera said, “Pfizer is trying to litigate its way to buying Metsera for a lower price than Novo Nordisk.” The company added that Pfizer’s litigation arguments “are nonsense, and Metsera will address them in court.”

The new suit escalates a heated standoff between Pfizer and Novo Nordisk over Metsera, whose obesity pipeline could yield new competitors in the booming weight loss drug market. Pfizer in September said that it would acquire Metsera for $4.9 billionor up to $7.3 billion with future payments – a deal that could be the company’s golden ticket to enter the space after struggling to bring its own obesity products to market.

But Novo Nordisk on Thursday launched a takeover bid valuing the biotech at around $6 billion, triggering a deadline of four business days for Pfizer to renegotiate its offer. On Friday, Pfizer filed its first lawsuit against Novo Nordisk and Metsera seeking to block the biotech from terminating its existing merger deal with Pfizer.

That suit, filed in the Delaware Court of Chancery, alleges that Novo Nordisk’s offer can’t qualify as a superior proposal because it’s not reasonably likely to be completed due to its significant regulatory risk.

Novo Nordisk helped establish the weight loss drug space, bringing to market highly effective GLP-1 drugs, including the diabetes injection Ozempic and obesity shot Wegovy. But the company has lost its leading position in the market to its chief rival, Eli Lilly

over the last year and has struggled to impress investors with its pipeline.