Janny Hu, Chronicle Staff Writer
Thursday, September 30, 2004

What was once the Greatest Show on Turf returns to San Francisco this weekend, toting a clear challenge for the *****' defense. St. Louis throws more and runs less than any team in the NFL, and if the *****' secondary doesn't tighten up, Sunday's prime-time game could morph into the greatest show on grass.

The Rams are averaging nearly 300 yards passing per game, while the ***** have given up 513 yards through the air over their last two outings. With some of those completions tracing back to sloppy play, coach Dennis Erickson has turned to trimming mental errors in preparation for the pass-happy Rams.

"You're going to give up passes in this league, we just don't want to give them up by making mental mistakes, by not being where we're supposed to be," Erickson said. "If a guy makes a catch and physically beats you, that's one thing. To not be at the right place when you should be, that's something that we can control."

The burden of stopping the Rams' offense will fall mainly on the secondary, which should get a boost with the return of starter Mike Rumph. He has healed sufficiently from his groin injury and will play right corner, sliding inside on nickel packages.

Watching last week's game from the sidelines, Rumph said he was impressed with the team's patchwork defensive line, as well as its run-stopping ability. Slowing the aerial attack, however, has proved difficult.

"With the Rams coming in (bringing) one of the top offenses every year consistently, it poses a threat to us," Rumph said. "Defensively, we had a couple of mental breakdowns (against Seattle) that allowed them to get plays on us. (We can't) try to do too much because (the Rams) have so many plays. You can't sit out there and try to match them play by play."

The Rams' play has been largely predictable so far. Their unbalanced offense has earned coach Mike Martz much criticism lately, as only 30 of the Rams' 110 plays have been runs. St. Louis has the league's two leading receivers in Isaac Bruce and Torry Holt, and quarterback Marc Bulger tops the NFC in pass completions (79) and attempts (114).

Still, the ***** say they don't want to get caught solely trying to defend the pass.

"You got to play those guys true," safety Ronnie Heard said. "You can't just rely on the pass because Marshall Faulk is in the backfield, and he can whip off 100 yards gained on seven carries if you're not playing to stop the run."

Rattay on pace: Quarterback Tim Rattay practiced Wednesday for the first time since separating his right shoulder during the season opener. If his arm continues to show improvement, he will be the starter against the Rams.

"Is he 100 percent? No. Is he getting toward that? Yes," Erickson said. "The thing that he did do is come out and make the right throws at the right places, the mental stuff he's been doing going through this rehab."

Rattay has suited up as the backup quarterback the past two weeks, without any practice time but with plenty of pain injections. He was sans shots Wednesday and does not plan to take any injections before Sunday.

"It feels much better today without shots than Sunday with shots, so I'm hoping I've turned the corner," he said.

Some of the credit might belong to Pro Bowl safety Tony Parrish, who suggested acupuncture to help Rattay's healing process. Parrish first tried the treatment when he tore ligaments in his left elbow and thumb during his first year with the team. He has been a regular user since, including this season on his calf.

"I was just at a point where I'm trying everything," Rattay said. "It's hard to tell (what effect it's had) since I'm doing so much, but it can't hurt and I think it's helping."

Briefly: Another week brings another defensive lineman for the ***** as Daleroy Stewart was signed on Monday. This is Stewart's third team this year; he began the season with the Cowboys and was later picked up by the Jets. Rams defensive back Aeneas Williams will return to free safety after one game at cornerback.

E-mail Janny Hu at jhu@sfchronicle.com.