ST. LOUIS -- There is more to the St. Louis Rams' turnaround than the startling rise of Marc Bulger from third-string quarterback. Quietly, the defense has salvaged what once seemed a lost season.

The Rams have won four straight games after an 0-5 start, and tonight can finally get to .500 with a victory over Chicago. The Bears (2-7) are caught in a tailspin, having lost seven in a row.

Bulger has been extraordinary while filling in for injured Kurt Warner, holding the NFL's best passer rating. Bulger has thrown 10 touchdown passes to just three interceptions and will be going for his fifth straight victory.

Still, he might be headed to the bench soon, with Warner expected to reclaim the starting job.

Warner is recovering from a broken pinkie and will be the backup tonight, although team doctors would prefer he not play this week to avoid risking injury.

"I'm just glad I'm not the one who has to make the decisions," wide receiver Torry Holt said. "Whoever is in there, we'll depend on them to make some plays."

Another concern is the health of Marshall Faulk. The star running back left last week's game with ankle and foot injuries and missed three practices this week. It's not clear if he will play.

"He's made remarkable progress each day so I wouldn't rule him out," coach Mike Martz said. "But I'm very pessimistic about it."

For all of Bulger's big numbers, and the threat posed by Faulk, consider the play of the Rams' defense: During the four-game winning streak, opponents have scored only one offensive touchdown a game.

St. Louis has forced 11 turnovers in that stretch, holding the Chargers to a season-low 126 yards passing last week. San Diego's final six possessions ended with four punts and two interceptions.

Defensive lineman "Tyoka Jackson walks into the room at halftime and says, 'We're not losing this one, we're just not losing this one,"' Martz said. "I'm proud of how they stood their ground. They could have gotten demoralized."

The Rams often use a unique 4-1-6 alignment that features a lone linebacker, Tommy Polley, and six defensive backs. Rookie Robert Thomas could start this week at linebacker, but whenever the opposition trots out three or more wide receivers, defensive coordinator Lovie Smith makes his countermove.

The defense has thrived despite the absence of All-Pro cornerback Aeneas Williams, who was lost for the season with ankle and leg injuries two weeks ago. Dre' Bly stepped up as the cornerback who takes on the opposition's best wideout. Last week, Bly also recovered an onside kick that set up the winning touchdown.

"I'm feeling pretty good about the way I have been contributing with Aeneas being down," Bly said. "Somebody has to step up, and I just take it upon myself to be that guy."

The Bears must try to find a way to stop the Rams' top-rated offense. Chicago's defense struggled in the second half last week against the Patriots, giving up 230 yards and allowing New England to score on its final five possessions.

Bears middle linebacker Brian Urlacher hopes Faulk plays, so he can face him for the first time.

"He's so fast and there is always a hole there for him," Urlacher said. "I am looking forward to playing against him."

The Rams rallied without Faulk against the Chargers. Bulger had 453 yards passing -- fourth most in franchise history -- and a team-record 36 completions in 48 attempts.

"Even games they lose, they're going to hit some plays," Bears defensive coordinator Greg Blache said. "And you can't get discombobulated when they hit a play, because they're going to hit some plays. We just have to be able to handle the storm and ride the tide, and when we get our opportunity, drop the handle on them."

Often-injured Chris Chandler, who left in the second quarter of last week's loss to the Patriots with a neck injury, gets the call at quarterback for the Bears. Jim Miller has tendinitis in his shoulder and elbow.

The Bears hope center Olin Kruetz, who underwent an appendectomy last week, will be able to play. If he can't, Kevin Dogins, who filled in for right guard Chris Villarrial earlier this season, would make his first career start at center.