The team will conduct tests on Sanders to confirm the injury.
Sanders was helped to the locker room by trainers just before the end of the open period during practice.
A two-time Pro Bowl selection, he leads the Broncos with 71 receptions and 868 yards this season. He also has four touchdown receptions for Denver, which has won three straight games to move to 6-6 on the season.
Sanders' 71 catches are his most since he had 101 catches in his first season with the Broncos in 2014.
Denver traded receiver Demaryius Thomas to the Houston Texans before the trading deadline and will have to rely on rookie Courtland Sutton (28 receptions, 558 yards, threeTDs) as its top target if the tests confirm Sanders' injury.