IRVING, Texas -- C.J. Spillman sort of smiled when it was brought to the attention of the newest Dallas Cowboys safety that he will play against his former team, the San Francisco 49ers, on Sunday at AT&T Stadium.

“It’s a business,” he said, “so treat it as nothing other than that.”

Spillman will enter the game knowing more about the Niners’ defensive and special-teams’ schemes than the Cowboys. He will play catch-up over the next few days to get a basic understanding of what Rod Marinelli wants from his safeties and what Rich Bisaccia wants from the special teams.

But Spillman's knowledge of San Francisco will help.

“Even though I might not schematically know what’s going on in-depth right now, I know the personnel and the guys and what they’re capable of doing,” said Spillman, who joined the Niners in 2010. “That will help me in the learning process.”

The Cowboys envision Spillman as a core special-teamer, which was his role with the Niners. He led San Francisco with 19 special-teams tackles last season. But coach Jason Garrett said Spillman could develop into a helpful member of the defense as the year goes on.

Garrett called it more of a coincidence that the Cowboys signed Spillman the week before they played his former team.

“I think we’ve all been in those situations where we’ve had a coach or a player from another team and you have conversations with those guys about different things,” Garrett said, “but for the most part, I think most teams do best when they trust their preparation that they would do off of film and base a lot of what they’re going to do from a game-plan standpoint on the film in the traditional way to evaluate. Sometimes, those things can be helpful to you. Sometimes, they can kind of confuse the issue. We brought him in here because we thought he was a good football player who could help our football team.”