Supermarket giant Wal-Mart, the world's largest retailer, has announced it will only sell high-definition DVDs in the Blu-ray format at its 4,000 US stores.
Blu-ray has got the upper hand on its rival format
The decision is viewed as a serious setback for the rival Toshiba-backed HD DVD format.
Wal-Mart said that customers had shown a clear preference for Blu-ray, developed by Sony, and the rival format would be phased out by June.
Wal-Mart follows a similar move by film rental firm Blockbuster.
The better picture quality and bigger capacity of next-generation DVDs and players were expected to help revitalise the $24bn global home DVD market
But, like the Betamax-VHS battle in the 1980s, having two DVD standards has dampened sales of both.
Analysts say it has frustrated both retailers and customers, who have to sell and buy products that could become obsolete very quickly.