The future of Denver Broncos halfback Terrell Davis is in question as he awaits the result of a Sunday MRI on his left knee. Though the injury might end up being minor, it could have a major impact on how the team feels about Davis, who has played only 17 games in the past three years.

Davis had his knee drained twice this week, but he was prepared to play Saturday night's game against the Bears. During warm-ups, the knee gave him problems and he had to be scratched. Davis was only expected to be on the field for about 15 plays.

Despite having a good training camp, Davis and the team have worried about his knees and legs for a long time. He is the team's starting halfback as long as he can stay healthy. The problem is staying healthy. Earlier this year, Davis had arthroscopic surgery on the left knee to clean out loose debris and allow him time to prepare for camp.

The right knee underwent reconstruction in 1999. The left knee has just been scoped. But with three other options at halfback available, Broncos coach Mike Shanahan might decide that losing Davis for a lengthy period could give the job to Orlandis Gary or rookie Clinton Portis. Mike Anderson, rookie of the year two years ago, could also be an option. He is currently at fullback.

It's too early to tell if the Broncos would ask the 29-year-old Davis to retire if the MRI results are bad. Davis had his MRI in Denver, and the result won't be determined until Monday.

John Clayton is a senior writer for ESPN.com.