DT Richard Seymour was placed on IR, likely ending his Raiders career. (US Presswire)

Starting DT Richard Seymour's season ended Thursday when the Raiders placed him on injured reserve.

Seymour missed the past seven games after suffering what he called a Grade 2 hamstring injury Nov. 4 against Tampa Bay. Barring a contract extension, Seymour will become a free agent in March, and he has likely played his last game as a Raider.

Last week Seymour said he believes he still plays "at an elite level" when healthy and wants to continue his NFL career next season.

Seymour came to the Raiders on Sept. 6, 2009 from New England in a trade for a first-round draft pick in 2011. Seymour made the Pro Bowl as a Raider in 2010 and 2011.

In his four seasons with Oakland, Seymour had 18.5 sacks, including three this year in just eight games. He's tied for second in sacks this year, half a sack behind team leader Matt Shaughnessy.

Seymour spent his first eight NFL seasons with the Patriots, winning three Super Bowls and making five Pro Bowls.

Raiders coach Dennis Allen said the team has not filled the open spot on their 53-man roster.

"We're going to keep it open right now," Allen said. "There are obviously options that we can do, but we're not going to do anything with it right now, and we'll make a decision later in the week how we want to fill that roster spot."

The Raiders, Allen said, could "potentially" promote someone from their eight-man practice squad. With starting CB Phillip Adams and SS Tyvon Branch injured, practice squad DB Cory Nelms is a candidate for promotion. Safety Akwasi Owusu-Ansah is also on the practice squad.

Injury report: Branch (ankle/neck), Adams (groin), starting RG Mike Brisiel (concussion/ankle) and backup RB Mike Goodson (illness) missed practice. Allen said that Brisiel has passed his concussion tests but is still sidelined by his sore ankle.

If Brisiel can't play Sunday, then rookie Tony Bergstrom will make his first NFL start.

"I'm just happy to help where I can," Bergstrom said. "I've always wanted to be an asset to this team to help us win. I'm looking to fill in wherever I can, and if it's at guard this week, then I'm more than happy to. That would be awesome.

"I feel confident in what I've been doing, feeling good at the position. We'll see what happens, but I feel ready to roll."

Raiders offensive coordinator Greg Knapp said he believes Bergstrom is ready to start if needed.

"I feel good about him. I like what I’ve seen in practice," Knapp said. "I also have seen the rookie mistakes that I know this might show up in a game. But I’m looking forward to get him some reps to see him play live if he has to play. He’s prepared. He’s one of the first guys in the building. When asked questions in meetings he’s always on top of his information and the right assignments. I feel like he’s ready to play now."

Mike Mitchell has been working with the first team at strong safety, and Brandian Ross has filled in for Adams at right cornerback.

Extra points: Allen said he was "a little bit" surprised that K Sebastian Janikowski didn't make the AFC Pro Bowl team. "Those are tough situations because (Cleveland's) Phil Dawson had a strong year also, but we certainly felt like Seabass was very deserving and very worthy of that honor."

Follow Raiders reporter Eric Gilmore on Twitter @CBSRaiders.