LONDON, Jan 31 (Reuters) - Novo Nordisk expects prices of its popular weight-loss drug Wegovy to fall as volumes of the weekly injection increase and Eli Lilly launches its rival therapy Zepbound in new markets, a senior executive said on Wednesday.

"We're really continuing to expand our supply capacity and our starter doses into the market, and competition will really be about expansion of supply," Chief Financial Officer Karsten Munk Knudsen said on a media call after the release of the company's fourth-quarter results. (Reporting by Jacob Gronholt-Pedersen and Maggie Fick; writing by Josephine Mason; editing by Jason Neely)