DETROIT -- Detroit Lions linebacker Travis Lewis was suspended Tuesday for the final four games of the regular season for violating the NFL's policy on performance-enhancing substances.

The 25-year-old Lewis is in his second season after being drafted in the seventh round in 2012. He has played 25 games for Detroit, with no starts, and his contributions have been mostly on special teams. Lewis is eligible to return Dec. 30, one day after Detroit's regular-season finale against Minnesota.

"All NFL players know they are responsible for their actions, and they also know there are consequences when their actions are not consistent with league policy," Lions general manager Martin Mayhew said. "While we are disappointed that Travis violated league policy and will miss the next four games, we expect that Travis will learn from this experience and not repeat it."

In a statement released by the team, Lewis apologized to his coaches, teammates, fans and team.

"I have let my team down and there's nothing worse than that," he said. "I will not make the same mistake again. I look forward to returning to the team after I serve my suspension."

To fill the roster spot, the Lions signed linebacker Julian Stanford. He played for the Jacksonville Jaguars last season.

The Lions are 7-5 and have what is in effect a two-game lead in the NFC North after beating Green Bay 40-10 on Thanksgiving and the Chicago Bears lost to Minnesota over the weekend. They will face the Eagles, also 7-5, on Sunday.

"We're really not trying to look too far into the future. Our destiny is on Sunday," wide receiver Nate Burleson said Tuesday. "What's most important is getting ready for a good Philadelphia team because they're playing on a high level."

Detroit's win over Green Bay came after two losses, at Pittsburgh and against Tampa Bay at home.

"I don't think we necessarily started looking ahead but in the flow of those games," Burleson said. "We kind of lost our focus and fire to finish."

Detroit turned the ball over five times in the 24-21 loss to Tampa Bay on Nov. 24, and even in their win over the Packers last Thursday, the Lions had four more turnovers.

"On the offensive side of the football, we just need to take better care of the football," quarterback Matthew Stafford. "If we can eliminate that, I feel real good about where we are."

Coach Jim Schwartz said his team needs to take better care of the ball, but turnovers are a byproduct of his team's offence.

"Part of that (turnovers) is being aggressive and pushing the ball down the field," he said. "There is some risk/reward in pushing the ball down the field. Some things we can do better in preventing turnovers."

Philadelphia quarterback Nick Foles has thrown 19 touchdown passes without an interception since taking over as the starter.

"He's been a good decision type guy. Not making mistakes and keeping his team in the game," Lions safety Glover Quin said.

Schwartz said that despite Foles' numbers the key to slowing down the Philadelphia offence will be limiting its running game, particularly running back LeSean McCoy.