"Today in rehab, the leg's still tight, the groin's still tight," said Jackson, who was hurt during last Sunday's 30-16 victory over the Washington Redskins. "So it's just one of those injuries where just time is what's really going to heal the injury. The most I can do now is still mentally prepare myself as if I'm going to go Sunday."
Jackson, who also missed practice Wednesday, acknowledged he didn't know if he would be able to go.
"I'm just going to continue to rehab and continue to be smart with it," he said. "I think that's the biggest thing, is to be smart with the injury."
If Jackson is unable to play, backup Kenneth Darby likely will make his first NFL start. Darby has been an infrequent contributor since signing with the Rams in 2008, but he scored the go-ahead touchdown against the Redskins on a 12-yard run.
Keith Toston, the other backup running back, played with a sprained shoulder most of the game against the Redskins. Chauncey Washington, a running back signed off the New York Jets' practice squad Tuesday night, also could be pressed into duty.
Pat Shurmer, the Rams' offensive coordinator, said his game plan will involve all possible players if Jackson doesn't play.
"We try to put the scheme together with the idea that our best players are going to be in there," Shurmer said. "Obviously, Steven being in the game is of some importance."
Darby rushed for 49 yards on a career-high 14 carries against the Redskins for an average of 3.5 yards per attempt.
"I thought (Darby) did a terrific job," Shurmer said. "The key to a role player is being able to come in and execute having had very few reps through the week."
Jackson didn't sound like he will play Sunday, but he didn't rule it out.
"That's definitely what we're going to come down to this weekend is, one, seeing if I can get through the game, and weighing this is a huge game for us," Jackson said. "This is Seattle at home, where we're only one game back in our division. Although it's early in the season, this game has a lot that come out victorious, that does a lot for us in our season. ... I will be there early Sunday seeing if I can run and cut and seeing if I can go out there and give my team a lift."
Copyright 2010 by The Associated Press