Cornerback Jimmy Smith is out indefinitely after having groin surgery on Thursday. (US Presswire)

Baltimore Ravens cornerback Jimmy Smith had surgery on his injured groin early Thursday and will be out indefinitely.

The Ravens expect him to return this season, but at this time it is unknown how many games he will miss. The groin injury flared up prior to Baltimore's 55-20 win over Oakland, which caused him to miss the game.

"Every time you lose somebody it has an impact," defensive coordinator Dean Pees said.

On Tuesday, the Ravens signed veteran cornerback Chris Johnson to add depth to the position in case Smith's injury would keep him out for a long period of time.

For the time being, cornerback Corey Graham will step into Smith's starting spot in the base defense, with second-year corner Chykie Brown coming into the game in nickel situations.

"That's a tough loss," Graham said. "Jimmy's made a lot of plays for us and has been with us all of last year and this year. It's big for us but other guys have to step up, make plays and get it done."

For the season, Smith has 28 tackles and three pass deflections. He became a starter this year after starter Laradrius Webb tore his left ACL in Week 6 against Dallas. The Ravens will now be without two of their top three cornerbacks.

Graham signed with Baltimore as a free agent this offseason so he can earn more playing time on defense. In his first five NFL seasons in Chicago, he played mostly on special teams.

Before signing, the Ravens told Graham he'd have a shot at playing some defensive snaps, which appears even more apparent now.

"Hopefully I'll get an opportunity to play more," Graham said. "I just have to go out there when I get a chance and make plays."

Follow Ravens reporter Jason Butt on Twitter @CBSRavens and @JasonButtCBS.