ALAMEDA, Calif. (AP) First-round pick Karl Joseph will have to wait a little bit longer until he can show the Oakland Raiders what he's capable of doing on the field.

As the Raiders held their first rookie minicamp practice on Friday, Joseph was merely a spectator as he continues to rehabilitate the torn ACL in his right knee that cut his final season at West Virginia short and raised questions about how high he'd be drafted.

The Raiders had no concerns as they believe Joseph will be completely healthy for his rookie season. Joseph said his rehab is on schedule and he plans to be ready to get back on the field when training camp starts in late July.

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''It's tough, just not being able to go out there and practice and learn the stuff, but I am still learning in meeting rooms,'' Joseph said. ''Right now, I am just focusing on rehabbing and getting healthy.''

The Raiders have big plans for Joseph, who is being counted on to replace the retired Charles Woodson. Joseph had five interceptions in four games before getting hurt last season and is known as a hard hitter despite his small size of 5-foot-10, 207 pounds.

Coach Jack Del Rio said it is important that Joseph make the most of this time even if he is unable to practice.

''We're still able to walk it and talk it so we're doing some of that,'' he said. ''It's definitely valuable time to have. We don't get enough time with these guys and we've got to maximize the time we do get and be really efficient with it.''

Del Rio even picked out Joseph's number, assigning him the No. 42 that Hall of Famer Ronnie Lott wore in a career that included two seasons with the Raiders.

''There have been a few good ones in that number,'' Del Rio said.

Joseph wore No. 8 in college and needed a new number as a pro. He said No. 42 was under consideration and he was happy when Del Rio picked it out. Joseph called it an honor and said he would represent it as best he can.

Joseph wasn't the only Oakland draft pick with questions about his knee. Some teams reportedly believed that second-round pick Jihad Ward would need arthroscopic surgery on his knee before he could play. The Raiders were confident that wasn't necessary and Ward was on the field and looked active in his first practice as a pro.

''He looked pretty good, right?'' Del Rio said. ''Don't trust all those reports out there. We felt pretty good about our reports. He looks terrific. He's very athletic.''

The Raiders had six draft picks, six other non-rookie roster players and 17 undrafted free agents on the field, along with several others there on a tryout basis.

This is the one chance for the rookies to get on the field and start learning the systems without the veterans. In just over a week, the Raiders will start organized team activities and then they will hold a three-day mandatory minicamp in June so there is little time for the new players to get acclimated.

''It was fast,'' third-round linebacker Shilique Calhoun said. ''That's the biggest thing for me. The transition is a little different because of how fast the game is and how fast the game is played. Then also, retaining knowledge. You have to be able to retain it pretty fast as well.''

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