Hoping to pull the winless Broncos out of an unprecedented tailspin, Denver coach Mike Shanahan on Wednesday also replaced starting quarterback Brian Griese with veteran Bubby Brister.

	Terrell Davis is escorted to the locker room by team doctors after he injured his knee.

Denver's train wreck of a season took another wrong turn Sunday when Davis tore two ligaments in his right knee while making a tackle after an interception in the first quarter of a 21-13 loss to the New York Jets.

Davis is scheduled to have reconstructive surgery in the next 10 days to repair the anterior cruciate ligament, the medial collateral ligament and cartilage. The recovery time is four to six months.

"Right now, my spirits are high," Davis said in an interview on ABC's Monday Night Football. "I know I'll be back 100 percent and I'll be as good as new. The type of person I am, my mentality, I'm a workhorse and I just want to get back and play with my teammates."

Davis' injury is the same one suffered by Atlanta running back Jamal Anderson in the first week of the season, leaving the NFL's two top rushers from a year ago out for the season.

"Obviously, he's working through it right now," Shanahan said of Davis. "I said, 'Hey, I love you. You've done everything we've asked you to do. Just hang in there.'"

After becoming the fourth player in NFL history to run for 2,000 yards in a season last year, Davis was faced with the challenge of succeeding without quarterback John Elway, who retired in May.

Davis had 211 yards on 67 carries in Denver's four games. He averaged 3.1 yards per rush, 1.7 yards below his career average.

In Davis' absence, the Broncos will turn to Derek Loville, whose last stint as a starter was with San Francisco in 1995.

"I didn't want it this way," Loville said. "I'd rather be 0-6 and have Terrell in there. That's my man. ... I spoke to him when he was getting a little treatment. He said, 'Hey, you've got to be a soldier.'"

The soldiers figure to be operating under a different platoon leader this Sunday against the Oakland Raiders.

After watching Griese struggle through four games, Shanahan said he is worried about damaging the second-year quarterback's psyche.

"I think it's tough any time you're 0-4 and you're the quarterback," Shanahan said Monday. "The pressure that you have in this town is overwhelming. For a young guy to come in, especially with the success that we've had, I think it does mount on you. I am worried about him. It's a lot to handle."

Brister, 4-0 as an emergency starter last year, was Elway's anointed successor in training camp, but lost his job in the preseason.

The unstable quarterback situation and Davis' injury are the latest obstacles that have impeded the Broncos since they won their second straight Super Bowl in January.

Elway's expected retirement announcement came in May, and linebacker John Mobley was charged with drunken driving nearly two months later. Mobley's season ended in Week 1 when he tore the ACL in his right knee.

Denver's off-field problems continued in September when linebacker Bill Romanowski was named as a subject in an investigation into illegal drug prescriptions.

And, of course, the Broncos are off to the worst start for a defending Super Bowl champion in a non-strike year.

"When it rains it pours," Loville said. "It's been tough. It's been tough this whole year -- losing John, now losing Terrell. It's rough"