Oregon has won eight games in a row and its 6-0 start to the Pacific-12 campaign is its best opening to a conference season in 87 years.
Singler scored 19 points and Arsalan Kazemi finished with 16, bringing Oregon back from a 10-point halftime deficit. The Ducks are 17-2 for the season and have won 19 in a row at home.
The Cougars (10-9, 1-5) were led by Mike Ladd with 19 points, eight rebounds and five assists.
Oregon was in the Pacific Coast Conference when it last started 6-0 in conference play, an achievement that came in 1926.