Running back Tony Dorsett of the Denver...

Running back Tony Dorsett of the Denver Broncos suffered a torn anterior cruciate ligament in his left knee and possible other damage, placing his career in jeopardy, team trainer Steve Antonopulos reported.

Dorsett, 35, will undergo arthroscopic surgery this morning.

He injured his knee while running a pass pattern Thursday. There was no contact, and the knee gave way when Dorsett planted his left leg to make a cut.

A test administered Friday afternoon in Denver disclosed the damage.

Besides the ligament tear, Antonopulos said Dorsett may have sustained cartilage and other ligament damage as well. The arthroscopic procedure should reveal the exact damage, the trainer said. Major reconstructive surgery then may be prescribed.