Dallas defensive end DeMarcus Lawrence has been ruled out against Tampa Bay on Sunday night with a back issue that limited him to a season-low 13 snaps last week.
Lawrence, suspended the first four games for violating the NFL's substance-abuse policy, missed practice all week. He was almost held out of last week's 10-7 loss to the New York Giants after his back flared up during the week.
The 24-year-old Lawrence has one sack in nine games after leading the Cowboys with eight last season, his second with Dallas.
The latest news from around North Texas.
The Cowboys lead the NFC with an 11-2 record.
Cornerback Morris Claiborne will miss his seventh straight game with a groin injury. He has said he hopes to return before the end of the regular season.
Backup tackle Chaz Green is out for the 10th straight game with a back injury.