ALLEN PARK, Mich. — Khyri Thornton missed the first six games of the season while suspended, and although the Detroit Lions played fine for a while without the defensive tackle, toward the end of his ban, a key teammate went down with a serious injury.

Haloti Ngata went on injured reserve a couple of weeks ago following an elbow injury, leaving Detroit without a crucial interior defensive lineman. That’s an area where Thornton may now be able to help.

“That was like the heart and soul of our defensive line, but at the end of the day, he always tells us, keep pushing forward, play for him,” Thornton said.

Thornton was suspended for violating the NFL’s substance-abuse policy, but he’s now eligible to return and the Lions activated him Monday.

Detroit is coming off an open date and will host Pittsburgh on Sunday night. The break in the schedule came after the Lions dropped two games in a row to fall to 3-3.

“Obviously, it came at a time that we needed it, when a couple guys went down and had some bumps and bruises,” wide receiver Marvin Jones said. “But it was great for the mind — to escape and just to take some time to reflect and then kind of let it pass by.”

Teams often talk about how the open date came at a good time for one reason or another, but the Lions in particular were reeling a bit. After a promising start to the season, Detroit lost to Carolinaand New Orleans , with the offensive line struggling to protect quarterback Matthew Stafford from jarring hits.

Thornton started six games last season, and his return could help on the defensive side. Punter Sam Martin — who has been on the reserve/non-football injury list — was at practice Monday, working off to the side a bit with other specialists during the portion open to reporters.

The big injury that’s been affecting the Lions all season has been tackle Taylor Decker’s shoulder problem. Coach Jim Caldwell didn’t say when Decker might return from the physically unable to perform list, but he gave an indication of the challenge he’ll face when he does.

“I think it’s just like anything else. It just takes a little time to get their timing back and physical nature of the game, and all of those things that go along with it,” Caldwell said. “It’s a process — best way I could explain it to you.”

The Steelers have won two in a row and have a two-game lead in the AFC North, so the Lions won’t have an easy matchup as they try to avoid a third straight loss. The extra week to prepare shouldn’t hurt.

“Just kind of gives you an opportunity to kind of look at yourself a little bit. You got a couple of extra days,” Caldwell said. “You do a little bit more self-scout, those kinds of things. But then also you get a chance to get a little ahead on the next opponent as well. So, you get a little extra viewing time in terms of preparation.”

Caldwell also said a week without a game can help players refocus, especially if their most recent game was a frustrating one.

“I mentioned last week a little bit that sometimes it’s not a bad thing to feel a bit of a pressure from a loss and things of that nature and stew on it a while, but then you get to a point too that you got to be able to put it behind you,” Caldwell said. “I think the bye week gives you a chance. You can fester through your bye week, and time to get back to work now.”

NOTES: DE Cornelius Washington said he didn’t have any specific information about why he was inactive for the game at New Orleans, and he wasn’t going to speculate. “That’s outside my pay grade,” he said. … The Lions waived QB Brad Kaaya.


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