** U.S.-listed shares of Danish drugmaker Novo Nordisk NOVOb.CO, NVO.N fall 1% to $49.07 premarket

** Co sues rival Eli Lilly LLY.N in a U.S. federal court accusing the U.S. drugmaker of false advertising in claiming its weight-loss medicines outperform Novo's drugs

** Shares of Lilly fall 0.7% premarket

** Novo alleges that Lilly violated federal and state false advertising and unfair competition laws, including the Lanham Act, through nationwide advertising campaigns for obesity drug Zepbound and diabetes treatment Mounjaro

** Novo says Lilly compared the highest approved doses of its medicines with lower doses of Novo's Wegovy and Ozempic while omitting newer, higher-dose versions that Novo says deliver greater weight loss

** Up to last close, NVO down 2.5% YTD