ALAMEDA, Calif. (AP) With less than two weeks before the Oakland Raiders' season-opener, Austin Howard doesn't have much time to ease into his role as the team's starting right tackle.

The job became Howard's when Menelik Watson suffered a season-ending ruptured Achilles tendon injury in Saturday's preseason loss to the Arizona Cardinals.

Howard worked with Oakland's starters in practice Tuesday, two days before he'll face Seattle Seahawks defensive end Michael Bennett in the preseason finale for both teams.

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It will be Howard's final tune-up before the Raiders open the regular season at home against the Cincinnati Bengals.

Generally the fourth preseason game is used to give the backups and players on the bubble increased playing time while the starters play minimally.

Raiders head coach Jack Del Rio isn't sure how much he'll play Howard against the Seahawks, even though the 6-foot-7-inch, 330-pound lineman has already played in a team-high 116 snaps this preseason.

''He's been getting time in the position so it's not a matter of getting time,'' Del Rio said. ''He played maybe more than he would have the other night but we'll make decisions on who's going to play and how much they're going to play as we get closer to the game.''

Howard clearly needs the work. He was already struggling to make the transition back to tackle after starting 16 games at right guard in 2014 and is the only tackle on Oakland's offensive line with negative grades in both pass blocking and run blocking this preseason, according to ProFootballFocus.com.

''It's been an adjustment,'' Howard said following the game with the Cardinals. ''Fortunately that's something I feel like I was able to do. Going on six years now, you kind of have to be used to going out there whenever you can be used.''

The Raiders signed Howard to a $30 million, five-year contract before the 2014 season with the belief he could be effective moving inside to guard despite being a two-year starter at tackle for the New York Jets.

The experiment lasted just one season and was scrapped when Oakland's new coaching staff took over this offseason.

In spite of Howard's slow progress, the Raiders remain encouraged.

Quarterback Derek Carr acknowledged the loss of Menelik as a significant blow but says Oakland has no other choice but to move forward.

''It is always hard when you lose anybody, especially up front,'' Carr said. ''That's the heart and soul of every team. To lose a guy like Menelik, it breaks my heart for him. For this football team, it hurts but you see it every year, someone has to come in and step up. It just happens to be us at that spot right now. We've actually had guys playing really well at that spot in practice and camp.''

One player whose playing status for Thursday's game is uncertain is linebacker Sio Moore.

A third-round draft pick in 2013 who started 22 games over the past two seasons, Moore was conspicuously absent from Oakland's defense during the game with Arizona. He played just 10 snaps, all of them on special teams.

Del Rio was noncommittal when asked if Moore might play on defense against Seattle.

''It's possible we'll get him in, yeah,'' Del Rio said. ''I'm not sure that I would try and describe it any other way than we're playing the guys that we need to get a look at. We'll continue to finish our evaluation through the last week.''

NOTES: Oakland officially released RB Trent Richardson, one day after the move was made public. Veteran KR Trindon Holliday also released as the Raiders made several moves to get down to the 75-player limit. CB James Dockery and Ras-I Dowling were also released, while the team waived QB Cody Fajardo, P Steven Clark, CB Rob Daniel, WR Josh Harper, WR Kenbrell Thompkins, G Lamar Mady and WR Milton Williams. S Jimmy Hall was waived/injured. ... Rookie TE Clive Walford did not practice.