ALAMEDA — The Raiders are catching a break this week in that they won’t face Pittsburgh Steelers star running back Le’Veon Bell.

Bell, the NFL’s second-leading rusher last season, suffered a season-ending knee injury when he tore his right medial collateral ligament Sunday, taking an important weapon away from the Steelers as they prepare to face the Oakland’s No. 2-ranked run defense. Veteran DeAngelo Williams will take his place.

“It’s never easy losing a guy, especially a guy like that who’s one of the best in the business,” Steelers quarterback Ben Roethlisberger said Wednesday on a conference call with Bay Area media. “We feel for him and everything he has to go through, but we have to have faith that DeAngelo will step up and carry the load for us.”

Williams is exactly why the Raiders aren’t breathing any sighs of relief.

“Really, it doesn’t look like it drops off,” Raiders coach Jack Del Rio said of facing Williams instead of Bell. “The guy is a really good back, so we’ve got our work cut out for us.”

Williams is a 10-year veteran in his first season with Pittsburgh after nine years in Carolina. He’s not the same back that rushed for 1,515 yards and 18 touchdowns in 2008, but he filled in capably when Bell was suspended for the first two games this season. Williams had 127 rushing yards in the Steelers’ opener, then scored three rushing touchdowns a week later in a blowout win over the 49ers. He stepped in last week after Bell went down and finished with 71 yards on just nine carries, plus another 39 yards receiving.

“He’s not Le’Veon, and he’s not going to try to be Le’Veon,” Roethlisberger said of Williams. “But he’s DeAngelo, and he’s done it in this league for a while now, and he’s done it at a high level.”

The Raiders, for all their success defending the run, aren’t taking anything for granted.

“It’s a week-to-week league,” Del Rio said. “We need to make sure that this week we’re good against the run, and this is one of the teams that runs it as well as anybody.”

Being stout against the run was a primary goal for the Raiders this season, and they’ve been particularly stingy the past five games. The Raiders haven’t allowed a team to top 100 rushing yards since Week 2 against Baltimore, giving up an average of 68.8 yards since.

They’ve built that defense around an infusion of personnel that includes free agent defensive tackle Dan Williams, second-round pick Mario Edwards Jr. and the continued progression of Khalil Mack.

Mack, who plays a mix of defensive end and outside linebacker depending on the Raiders’ alignment, is rated by Pro Football Focus as the NFL’s No. 2 edge defender. The website credits him with a run stop percentage (the amount of times he stuffs a run for a minimal gain based on the down and distance) of 13.4 percent. The next highest 3-4 outside linebacker, which is where PFF classifies Mack, is Jadeveon Clowney and Elvis Dumervil at 9.5 percent.

Steelers coach Mike Tomlin is impressed by the Raiders’ group up front.

“Those guys are doing a really good job of utilizing their hands, controlling the line of scrimmage and being ball aware,” Tomlin said. “Seeing it consistently from guys like Mack and Mario Edwards and Dan Williams. It starts inside and up front, and they’re getting those type of contributions from those men and others.”

Mack didn’t practice Wednesday with the Raiders injury report listing him with a hamstring injury. He hobbled off the field toward the end of Sunday’s win over the Jets, although Del Rio said after the game there was no injury to report. It’s likely Mack was just getting some rest as he has been banged up several times this year. He moved around well while stretching with the team before practice began. Safety Charles Woodson also took his normal Wednesday rest day. TJ Carrie was limited with shoulder and hip injuries.