The Ducks (19-6, 8-4 Pac-12) trailed by 12 points early in the second half but went on a 10-0 run in the waning minutes to overtake the Buffaloes (19-6, 8-4). The two teams are tied for the league lead.
Richardson also had nine rebounds. Payton Pritchard added 15 points for the Ducks.
Evan Battey and D’Shawn Schwartz each had 14 points for Colorado.
The Buffaloes went on a 20-0 run to build a 30-16 lead while the Ducks missed 11 consecutive field goal attempts and were called for a pair of charges.
Colorado led 35-26 at halftime, shooting 48% from the field (14 for 29) after a cold start while the Ducks shot 32% in the opening half (10 for 31).
Oregon’s deficit grew to 12 points before the Ducks rallied within 43-40 with 13 minutes left but Colorado answered with 3-pointers from Schwartz and Lucas Siewert to push the lead back to nine points.
The Ducks drew within two points at 51-49 and 55-53 and had possession but couldn’t convert and finally Richardson’s two free throws with 4:18 left knotted the game at 58-58.
Richardson then hit a 3-pointers for Oregon’s first lead since the opening minutes.
Colorado: This is the latest in a season that the Buffaloes have been atop their league since the 1968-69 season when they shared the Big Eight lead with Kansas. Colorado went on to win the conference title that year, it’s last regular-season championship.
Oregon: Colorado was the seventh top 25 opponent this season for Oregon, the most since the Ducks played seven in the 2008-09 season. Oregon has only once played eight ranked opponents in the regular season, in 1994-95.
Oregon’s 6-foot-11 freshmab N’Faly Dante missed his sixth consecutive game due to a knee injury. The Ducks did regain 6-9 sophomore Francis Okoro, who missed last week’s game at Oregon State while attending his father’s funeral in Nigeria.
Colorado: Plays at Oregon State on Saturday.
Oregon: Hosts Utah on Sunday .