ALAMEDA, Calif. (AP) -- Long after practice began, Oakland Raiders defensive tackle Richard Seymour and five of his injured teammates - including four projected starters - slowly made their way out to watch the workout.
The debate over whether any of the six will play in Thursday's preseason finale in Seattle has morphed into concern about their availability for the season opener against San Diego on Sept. 10.
Seymour, who turns 33 in October, is nursing tendinitis in his knees. Center Stefen Wisniewski (calf) and wide receivers Denarius Moore (hamstring) and Jacoby Ford (ankle) have also been out while linebacker Aaron Curry has been on the physically unable to perform list since camp began. Reserve cornerback Pat Lee recently joined the walking wounded with a sore back.
That list doesn't include kicker Sebastian Janikowski, who injured his groin on a kickoff last week in Arizona. Janikowski has been cleared to practice but the Raiders (tied for No. 23 in the AP Pro32) say they might be tempted to hold him out the remainder of the preseason.
Oakland coach Dennis Allen has not ruled any of the other six out for the opener, but the team signed return specialist Roscoe Parrish on Tuesday and will have him returning punts against the Seahawks.
''We're watching the waiver wires to see if there's anybody that we feel (has) a chance to help us,'' Allen said. ''We'll get a chance to get (Parrish) out there to return some kicks on Thursday night and see what we've got.''
Parrish joined the Raiders one day after getting released by San Diego. He had signed a one-year contract with the Chargers in the offseason but was buried on the depth chart at receiver and lost out to Michael Spurlock in the battle for punt return duties.
With Oakland, Parrish will handle the punt return chores until Ford or Moore returns.
A second-round pick for Buffalo in 2005, Parrish led the NFL in punt return average in 2007 (16.3) and '08 (15.3), becoming the first player in league history to do so in consecutive seasons.
''I actually woke up as a Charger and went to sleep as a Raider,'' said Parrish, who missed all but two games in 2011 after suffering a season-ending ankle injury in a Week 2 loss to Oakland. ''Coming over here when they need a returner is a good feeling because that's what I do. I'm not going to take anything for granted ... but I look forward to being in that black and silver.''
Parrish's signing fills an immediate need but the rest of the Raiders injury situation remains clouded.
Moore, who caught 33 passes as a rookie last season when he was quarterback Carson Palmer's favorite deep threat, missed most of training camp after injuring his hamstring in practice. Ford, limited to eight games in 2011 with an ankle injury, only recently got out of a walking boot after getting hurt against Arizona on Aug. 17.
That opened the door for rookie receivers Juron Criner and Rod Streater to get increased reps in practice but it has also hurt the timing of the rest of the offense.
''We need a ton of work together,'' Palmer said. ''When they're back, it's not easy to get off the couch or get out of a walking boot or off crutches or whatever it may be and just show up and play. This league is way too good.''
Wisniewski has already been declared out for the preseason finale in Seattle, as has Curry.
The veteran linebacker underwent a stem cell procedure on his knees in the offseason and spent a week in Los Angeles during training camp getting additional treatment but has yet to be cleared to practice. If he is still on the PUP list as of Friday, Curry would have to sit out the first six weeks of the regular season.
Seymour, coming off his seventh Pro Bowl season, has missed Oakland's last two preseason games while resting sore knees. Allen originally said Seymour had arthritis in his knees but later changed it to tendinitis.
''It's just something we'll have to manage as we go throughout the season,'' Allen said.
To clear room on the roster for Parrish, the Raiders waived/injured offensive lineman Zach Hurd.
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