CHENEY, Wash. -- Seattle Seahawks coach Mike Holmgren said top wide receiver Darrell Jackson likely will not play until the team's Aug. 26 exhibition game at San Diego.

Jackson, who had a career-high 87 receptions in 2004, had surgery on his right knee Oct. 12 to repair torn cartilage. He missed 10 games but returned to catch 20 passes in three playoff games, including five for 50 yards in Seattle's Super Bowl loss to Pittsburgh.

But weeks after that game, Jackson had a second knee surgery. He is watching training camp practices from the sidelines wearing his practice jersey, team visor and a smile.

"He's on a program to get his leg straightened," Holmgren said Thursday. "His knee is pretty good, but his muscles in his quad and so on have to be stronger, so he doesn't re-injure anything.

"He's right on schedule. We're setting a target date of the third preseason game."

Holmgren also said that D.J. Hackett, who had been getting Jackson's preseason practice plays with the first-team offense, will miss two to three weeks with a strained right hamstring. Hackett was injured while catching a pass in the end zone on the final play of Wednesday morning's practice.

Hackett, who caught 28 passes with two touchdowns last season, spent Thursday watching practice with an electric stimulation device wrapped to the top of his right leg. He limped while walking slowly.

Seattle's passing game is already missing starting tight end Jerramy Stevens. He has said team trainers expect him to be out until the third week of August following April 25 surgery on his left knee.

Defensive back and special-teams player Jimmy Williams twisted his ankle during drills Thursday morning and was limping noticeably on his way off the field. His prognosis was not immediately known.