Charles Rhodes scored a career-high 34 points and the eighth-seeded Bulldogs came back from a 13-point second-half deficit to beat the Ducks.
Mississippi State trailed 41-28 after Malik Hairston's 3-pointer at the start of the second half, but Oregon didn't make another 3 until the final seconds, finishing 9-for-38 overall.
Barry Stewart's third 3 pulled the Bulldogs within one at 52-51. Rhodes then put Mississippi State (23-10) ahead with a dunk, and the Bulldogs finally took control.
Malik Hairston scored 22 points for Oregon, but when the Ducks (18-14) stopped making outside shots, their offense went into disarray. That was the case for most of the second half.