By Jim Thomas

Rams coach Jim Haslett is taking a "show-me" approach to Steven Jackson's availability for Sunday's game against the New York Jets. Unless Jackson shows he can perform full speed for an entire practice sometime this week, Jackson will not play.

"Steven's got to give us a full day's work this week," Haslett said Monday. "We can't go into the game not knowing whether he can play or not. So we just decided that we're going to make sure that he can actually go in practice, and not just jog through."

After a practice week in which Jackson got limited work during team

"We worked him out (in pregame) Sunday and he said he felt good," Haslett said.

When the Rams' offense trotted out for their first series of the day Sunday, Jackson was in the huddle. But before the Rams broke the huddle for their first play, Antonio Pittman had replaced Jackson. What happened?

With his strained right thigh muscle not 100 percent, Jackson said he wasn't comfortable running the play once he heard the call.

"The play call was really more of an outside play, a cutback play," Haslett said. "He didn't think he was ready for that play. ... It kind of caught everybody off guard."

That set off alarm bells on the Rams' sideline, and things got worse from there. Much worse. On his first carry of the game the play that Jackson originally was scheduled to run Antonio Pittman suffered a hamstring injury.

Not much later, Travis Minor suffered a concussion on special teams, ending his day. With Kenneth Darby on the pregame inactive list, that left the Rams without a healthy running back.

So as Haslett pointed out, offensive coordinator Al Saunders quickly found himself in a play-calling pickle.

"Because you have a set of plays for (Jackson), you have a set of plays for Pittman ... and a package for Minor," Haslett said. "All of a sudden, the first play (Jackson) can't go, the second play he's not 100 percent. And we're in a state of flux the whole game trying to call a game."

Pittman gutted it out on the hamstring injury. He couldn't run with a burst and finished with 12 yards on 10 carries. Jackson ran seven times for 17 yards, participating in only two plays in the second half. When your quarterback is the team's leading rusher, that's not a good sign. Such was the case in the Rams' 34-13 loss to Arizona, with Marc Bulger scrambling three times for 32 yards.

On Monday, Haslett all but ruled out Pittman for the Jets game because of the hamstring injury, saying, "I think he will be out this week."

Minor is scheduled for a neuro-psyche test today to gauge whether he still is feeling effects of the concussion. In most cases, players who suffer concussions are held out at least one week. So if Jackson can't take part in at least one full-speed practice either Wednesday, Thursday, or Friday, Darby could be the only available running back against the Jets.

"There's not much you can do," Haslett said. "You've got to go with the guys you have. Would you rather have three guys out there that are injured? Or somebody that's at least healthy? That's the situation we're in right now."

Haslett said the team is evaluating potential street free agents at running back, but there's not much available at this time of the year. Another possibility is Lance Ball, who was in training camp with the Rams and currently is on the Indianapolis practice squad.

"He's a guy that would at least have an idea of what we're doing," Haslett said.

Otherwise, the options could very well be Darby ... Darby ... and Darby.

"He's a slasher," Haslett said. "I think he's very strong. He runs low to the ground, he's a tough kid. I've got confidence in him that he'll go in there and do a good job."

Darby, 5-feet-10 and 211 pounds, was signed by the Rams off Atlanta's practice squad Oct. 14, so he has had only three weeks of practice with the team. He saw action on special teams against Dallas and New England. Against the Patriots, he had a 3-yard gain in the second quarter, but the play was nullified by a holding penalty against guard Jacob Bell.

As for Jackson, he said after the Arizona game that he didn't think his injury felt any worse. But on Monday, he told Haslett that he was a little sore.