Brown converted 11-of-13 free throws for the Cowboys (11-1), who shot 52.1 percent from the field and won despite being outrebounded 41-29.
Marcus Smart netted 18 points and Phil Forte sank four 3-pointers on his way to 16 points.
Le'Bryan Nash added 15 and grabbed six rebounds for OSU.
Josh Scott provided 20 points and 12 rebounds for the Buffaloes (10-2). Askia Booker put in 19 points and Spencer Dinwiddie added 18.
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