Target Corp., the nation's second-largest retailer, will start selling a Sony Blu-ray high-definition DVD player during the critical holiday shopping period and feature the player along with Blu-ray discs in store displays, dealing a potential blow to the rival HD DVD format.

The move, which the companies will formally announce Thursday, is another step in resolving a format war that has kept confused consumers from rushing to buy new DVD players until they can determine which format will dominate the market.

Target said it will sell the Sony BDP-S300 for $499 in October and display it along with Blu-ray DVDs from three studios, including Sony Corp. and The Walt Disney Co., at the ends of store aisles.

The Target announcement comes five weeks after a decision by video rental chain Blockbuster Inc. to offer only Blu-ray titles when it expands its high-def offerings this fall.

Blu-ray is backed by Sony, which developed it. Most Hollywood studios are releasing films either exclusively in Blu-ray or together with the rival HD DVD format, which is backed by its developer, Toshiba Corp.

Only Universal Studios, a unit of General Electric Corp., is releasing films exclusively in HD DVD.

Both formats offer a high-definition picture that is crisper and brighter than standard DVDs, as well as more storage that allows interactive features and games to be packaged with movies.

Consumers have been slow to embrace either format, worried they might get stuck with a losing technology.

Target does not sell high-def DVD players in its stores, although it does sell a Toshiba HD DVD player for $299 on its Web site.