The Chargers (5-8) have the fourth-worst record in the AFC, are the only team in the West already eliminated from playoff contention and are riding a two-game losing streak.
That game at the Oakland Coliseum in Week 5 also marked the debut of Chargers first-round pick Joey Bosa,DeAndre Jordan Jersey. Bosa had two sacks of the Raiders' Derek Carr and had three tackles for losses on the day.
Yet Penn says you wouldn't know it from watching San Diego on film. For that reason alone, Penn has his concerns heading into Sunday's road game.
"They don't get talked about enough, but they have a lot of good guys on their (defense)," Penn said.
The Raiders' offensive line has held up well for most of the season, allowing just 13 sacks in 13 games — the fewest in the NFL. That should make for another intriguing matchup.
That shouldn't be a problem considering that Oakland has a chance to clinch its first playoff berth since 2002. Beating the Chargers puts the Raiders in; a loss and they'll need some help to qualify this weekend.
ALAMEDA, Calif. (AP) — Of the three remaining teams on the Oakland Raiders' regular-season schedule, left tackle Donald Penn might be most worried about this week's game in San Diego.
NOTES: First-round pick Karl Joseph (toe) did not practice and was seen walking gingerly in the Raiders' locker room. Wide receivers Michael Crabtree (finger) and Amari Cooper (shoulder) were limited. Left guard Kelechi Osemele (knee) and linebackers Perry Riley Jr. (hamstring) and Malcolm Smith (hamstring) were also limited. ... Backup defensive tackle Stacy McGee (ankle) and linebacker Shilique Calhoun (knee) were held out of practice.
While San Diego is making a final push before heading into the offseason, the Raiders are trying to rebound from one of their worst games of the season after losing 21-13 in Kansas City last week.
"The biggest group we faced this year," Bosa said of Oakland's offensive line. "Tough group. They'll maul you off the ball if you're not playing good technique and you're not playing fundamentally sound. We just have to come into this game and attack it the same way we did in Week 5."

"I think that's why we've been successful because we don't look ahead," Penn said. "We take it one week at a time. That's big,Cheap China Jerseys, especially with having a young team like we do.
"The thing is,Wholesale Nike Shoes Cheap, you watch their film,Wholesale MLB Jerseys, they're playing still like they're in the mix of things and that's the scary part,Adidas Superstar Clearance Sale," Penn said Thursday.
Penn doesn't think that will be an issue against a division rival.
Oakland won the first matchup earlier this season when San Diego botched a potential game-tying field goal late in the fourth quarter.
"It's big because some of the young guys could start thinking ahead, start looking ahead. But keeping that even keel, going week by week, gets you to focus more on that week and on that plan."
"Bosa's really come along this year. He moved all over in that game. He's been doing that all year. He's still moving around on the film I watch."
Penn spent part of the game matched up against Bosa and will face him again on Sunday. Because the Chargers like to move Bosa around on the defensive line, Raiders right tackle Austin Howard will get his shot at Bosa, too.
"We have to make sure we go in there and take care of our business and make sure we're on point with everything and don't take these guys lightly."