Wetzler yielded three runs on eight hits with six strikeouts for the Beavers, who advanced to take on Indiana in a Wednesday elimination match-up.
Max Gordon and Dylan Davis each provided two RBI for Oregon State, which was leading 3-0 before breaking the game open with seven runs in the fourth.
Louisville starter Jeff Thompson was roughed up for seven runs (three earned) on seven hits in 3 2/3 innings.
The Cardinals were bounced after also falling to Indiana in the first game of the College World Series.
Swim Week Miami Beach 2014 [PHOTOS]