Source: Ratliff expected to play

Cowboys Pro Bowl nose tackle Jay Ratliff plans to play Sunday despite a bruised right knee, a source close to the team said.

Ratliff bruised the knee during Thursday's practice and sat out the final practice of the week on Friday. An MRI did not reveal any ligament damage, and Ratliff has undergone treatment including electrical stimulation the last two days. He is officially listed as questionable.

"If he wakes up and isn't feeling it, then all bets are off," the source said. "But right now, he's planning on giving it a go."

Ratliff has 31 tackles, including a team-high five for losses. He is a fixture in the team's nickel and dime packages, a rarity for a 3-4 nose tackle. Ratliff is tied for second on the Cowboys with two sacks and has 10 quarterback pressures.

If Ratliff cannot play, Junior Siavii will take his place in the starting lineup. The 6-foot-5, 320-pound Siavii has been out of football the last three seasons, but he's been effective playing about 15 snaps per game as Ratliff's backup. Defensive end Marcus Spears would also get some work at nose tackle. Defensive end Jason Hatcher would replace Ratliff as an interior rusher in the nickel and dime packages.

Tim MacMahon covers the Cowboys for ESPNDallas.com. E-mail tim.macmahon@espn3.com.