ALLEN PARK, Mich. — With a 30-20 loss to the Green Bay Packers in Week 17, the Detroit Lions fell to the No. 6 seed in the NFC and will travel to Dallas for a first-round matchup with the Cowboys on Sunday (4:40 p.m. ET), but their best defensive player will not be on the field.

The NFL suspended All-Pro defensive tackle Ndamukong Suh for one game without pay for stepping on Packers quarterback Aaron Rodgers’ injured left calf. NFL Vice President of Football Operations Merton Hanks imposed the suspension and sent a letter to Suh outlining the reasoning behind the ruling.

“You did not respond in the manner of someone who had lost his balance and accidentally contacted another player who was lying on the ground,” Hanks wrote. “This illegal contact, specifically the second step and push off with your left foot, clearly could have been avoided.

“You unnecessarily stepped on your opponent’s unprotected leg as he lay on the ground unable to protect himself.”

Suh will appeal the suspension to former player Ted Cottrell, who is jointly appointed by the NFL and NFL Players Association to rule on appeals of on-field incidents, and Suh can have his appeal process expedited with a decision as early as Tuesday.

History suggests Suh’s suspension will likely be upheld, but Cottrell did overturn a one-game suspension for former Baltimore Ravens safety Ed Reed in 2012, reducing his punishment to a $50,000 fine for a third helmet-to-helmet hit in three years.

In Sunday’s game, the Lions struggled in all three phases. Quarterback Matthew Stafford was inaccurate, completing 20 of 41 passes for 217 yards with three touchdowns and one lost fumble. On special teams, they gave up a 55-yard punt return touchdown to Micah Hyde in the first quarter and had a few other blunders that cost them needed field position. The defense couldn’t stop the run, allowing 152 yards on the ground, or pressure a hobbled Rodgers, finishing with just one sack that came during Matt Flynn’s four plays of relief.

Now, what had been a stout defense will be without Suh, who led the Lions with 8.5 sacks and was second with 13 tackles for loss in the regular season. Suh will also likely be named a first-team All-Pro for the third time in his five NFL seasons after being the top player on the league’s No. 2 overall defense.

“He’s a dominant force in our defense,” Lions strong safety James Ihedigbo said. “He’s kind of the key centerpiece, but we have faith that guys are going to step up and fill that void and do the best job they can to get this win.”

Now, without Suh, the Lions will have to stop a Cowboys offense that has the NFL’s No. 2 rushing attack.

–Right guard Larry Warford exited in the second quarter with a left knee injury and didn’t return after being carted off, but he still hopes to return in the postseason.

“Hopefully get my knee better,” Warford said when asked what he plans to do this week. “Whatever they say. If I’m ready to go or not, it’s up to them. It’s day to day.”

Day to day is an optimistic outlook based on how Warford exited the game, walking gingerly toward the trainer’s table in the second quarter and heading to the locker room shortly thereafter, but the Lions still think there’s a chance he’ll play against the Cowboys.

“Not ruled out at this stage, but not certain yet,” coach Jim Caldwell said. “We’ll have to see.”

Warford declined to provide further detail on his injury Monday. He missed three games earlier this year with a left knee injury, too, and has played well in the four games since he returned.

If Warford can’t play, rookie Travis Swanson would start at right tackle.

–The Lions reinstated center Dominic Raiola Monday after his one-game suspension, and he spoke publicly for the first time since the NFL handed down the suspension last Monday. Swanson started in his place.

“I was disappointed, but that’s the way they saw it,” Raiola said. “Apparently, they didn’t hear what I had to say and that’s the way it is and that’s the way it went. It was a rough week – probably one of the more difficult weeks of my life. It was tough.”

Center Darren Keyton was waived to make room for Raiola.