EUGENE, Ore. -- Oregon running back De'Anthony Thomas is unlikely to play against Colorado this weekend after emerging from practice wearing a boot on his injured right ankle.

Running backs coach Gary Campbell told reporters on Tuesday that his return is "not going to happen" when the No. 2 Ducks (4-0, 1-0 Pac-12) visit Colorado (2-1, 0-0) on Saturday.

Thomas was injured on the opening kickoff of second-ranked Oregon's 55-16 victory against California on Saturday night, slipping on turf that was slick from a driving rain.

Thomas has rushed for 338 yards rushing and six touchdowns this season. He also has 485 all-purpose yards through three games.