GREELEY, Colo. -- Results from an MRI exam on Terrell Davis' swollen left knee showed no structural damage, but Denver's star running back isn't sure when he'll be able to practice again.

	Davis

Davis, who's had four knee surgeries in three years, had a cortisone shot on Monday to reduce the swelling and another injection to help ease a detiorating arthritic condition discovered in his knee.

"They didn't see anything that required surgery," Davis said. "I was hoping it could have been a better situation if they had seen something and said this is it. There are a lot of different variables now. It is obviously not clear. We will see and go from there."

Davis, who had surgery on his left knee twice this past year, had been running hard and seemingly pain-free during training camp. He had fluid drained from his knee twice during camp, but still expected to play in Denver's preseason opener against Chicago last Saturday.

Davis warmed up with the team before the game, but had so much swelling and pain in his knee that he told the coaches he couldn't go.

"The knee felt like someone had a staple gun and shot it into the side of my knee," Davis said. "The pain was associated with weakness. I couldn't have played in the biggest day of my life."

Davis was the league's MVP in 1998 after rushing for 2,008 yards, but tore the anterior cruciate ligament in his right knee in the fourth game of the 1999 season. Leg and foot injuries limited him to just 13 games the past two seasons.

``I don't think anybody knows the answer to the questions: How much will he play? How long can he play? Will he hold up?" Broncos coach Mike Shanahan said. ``We'll just have to wait and see."

Davis had arthroscopic surgery on his left knee to remove loose fibers from under his kneecap in May, but was back on the field for a minicamp just three weeks later.

Davis said he was surprised by the flareup on Saturday, but expected to be bothered by some wear and tear after having so many surgeries.

"It wasn't like one event happened and all of a sudden here we are faced with this situation," Davis said. "It has been there the last couple of years and I've thought about it. I thought by this time the knee would be better, but as you get older the situation gets worse. So now I am faced with this dilemma. We will see what happens."

Davis' latest setback would seem to put the Broncos in a bind, but their depth at running back should allow the team to wait for him to heal fully.

Olandis Gary, who rushed for a Broncos' rookie record of 1,159 yards in 1999, is back after tearing his ACL last season, and Mike Anderson has made a successful switch from tailback to fullback.

The Broncos also have rookie Clinton Portis, their second-round draft pick out of Miami, who has dazzled the coaching staff with his speed and elusiveness.

"One of the reasons I can be patient is we are going to have all these other running backs get all the reps," Shanahan said. "TD knows the offense and knows the system. He really doesn't need a lot of reps so he won't take away from the other guys."

Shanahan said Davis could start next Monday against San Francisco if his knee improves enough, but that Gary and Portis will likely get most of the work in practice.

"The question is can he get enough work on the scout team where he feels comfortable that he can go into a game and be in football shape," Shanahan said.