Tony Romo won’t play against San Diego on Thursday in the Cowboys’ preseason opener. But tight end Jason Witten and running backs DeMarco Murray and Lance Dunbar are also expected to sit out the game, according to a source.

This isn’t a surprise. Last season, Romo, Murray and Witten were held out of the team’s first exhibition game against Miami in Canton, Ohio.

Meanwhile, the Cowboys appear to be taking precautions with Dunbar, who has participated in all training camp practices but is only eight months removed from surgery to repair damage in the posterolateral corner of his left knee.