Tennessee Titans safety Michael Griffin lost his appeal of a one-game suspension as a repeat offender of the league's rules prohibiting hits to the head and neck area of defenseless players.

The safety says the NFL couldn't tell him what he should have done to avoid this situation Sunday on his hit of Raiders tight end Mychal Rivera.

"I asked them what should I have done differently, and (appeals officer Matt Birk) told me there's no clear black and white answer," Griffin said Tuesday night on his weekly radio show.

Griffin was flagged for unnecessary roughness in the second quarter of a 23-19 win over the Raiders. He went low, hitting Rivera as the tight end went to the ground after attempting a catch. It was Griffin's second violation this season and fourth since 2011.

The safety said Tuesday night that video clearly shows him running down the 15-yard line with Rivera catching the ball at the 20 and falling after his second step. Griffin said he went to his right knee before they collided, and he also pointed to photos showing Rivera's chin strap wasn't buckled; that might have caused the tight end's helmet to pop off.

"They tell me to go low," Griffin said. "Now when the receiver goes low, I don't know where I'm supposed to do now. Just let him catch the ball?"

The suspension will cost Griffin $205,882.35 of his $3.5 million base pay.

Packers: Aaron Rodgers returned to practice for the first time since he fractured his left collarbone on Nov. 4, though the All-Pro quarterback isn't likely healed enough to play Thursday against Detroit. Green Bay hasn't announced a starter, but it is expected to be Matt Flynn, who took starter reps two days after helping to lead the Packers back from a 16-point deficit in the fourth quarter to tie the Vikings in overtime.

Colts: Owner Jim Irsay issued a wake-up call to his team in a series of Twitter posts, calling on them to find a way to win the division title, accentuate the team's strengths, limit the weaknesses and "get our heads out of r butts-WAKE UP!" The comments came two days after the Colts lost 40-11 at Arizona. Irsay has criticized his team on Twitter two other times this season.