Cooper has trended in the right direction all week since missing last Sunday's win over the New York Giants because of a sprained left ankle and concussion. He cleared the concussion protocol Wednesday then practiced on a limited basis Friday.
Team sources told ESPN's Dan Graziano that the Raiders had entered Friday under the impression that Cooper was not going to practice and would miss Sunday's game. Cooper went to the trainers and said he would like to try to practice, and they agreed to see how he did. He participated in practice and "looked pretty good," according to one source.
Cooper, who has 42 catches for 499 yards and five touchdowns this season, was injured on a hit by Broncos safety Darian Stewart that was flagged for unnecessary roughness during the Raiders' 21-14 win over Denver on Nov. 26.
In the Raiders' 31-30 defeat of the Chiefs on Oct. 19, Cooper had 11 receptions for a career-high 210 yards and two touchdowns.
Information from ESPN's Paul Gutierrez was used in this report.