OMAHA, Neb. -- Oregon State first baseman KJ Harrison launched a grand slam Monday night, and right-hander Bryce Fehmel limited LSU to one run through eight innings as the Beavers posted a 13-1 College World Series win over the Tigers at TD Ameritrade Park.
Oregon State, which won its 23rd straight game, improved to 56-4 on the year. The Beavers will play at 2 p.m. Friday against the winner of Wednesday's 6 p.m. matchup between LSU and Florida State. The loser of Wednesday's LSU-Florida State game will be eliminated from the CWS.
LSU, which saw its 17-game win streak end Monday night, dropped to 49-18 this season.
"It wasn't what we expected or hoped for, obviously," said LSU coach Paul Mainieri. "A heck of a way for a 17-game winning streak to end. But just right from the start things didn't go well for us."
LSU starting pitcher Eric Walker had to leave the game while facing the leadoff hitter in the top of the third inning due to a fatigued muscle in his right forearm. Walker (8-2) was charged with the loss, as he worked two innings, allowing one run on two hits with no walks and no strikeouts.
"It looked like Eric was settling in, was going to do great," Mainieri said, "and his forearm tightened up again, which is what happened a week ago after an intrasquad game. He had gone through a bunch of rehab and threw a couple of side sessions and felt great, felt 100 percent. His warm-ups today in the bullpen were great. His first two innings were great. And then on the third pitch of his warm-ups for the third inning, he just felt it tighten up again.
"And so obviously we had to take him out. We don't think it's anything serious. We think it's just a fatigued muscle. He's pitched more innings this year than he ever has, and I think he's running a little bit dry. So we'll see if he'll be available if we're fortunate enough to make it to the final round."
Fehmel (6-2) pitched brilliantly for the Beavers, limiting LSU to one run on two hits in eight innings with three walks and three strikeouts.
Harrison helped pace the Beavers' 11-hit attack with a sixth-inning grand slam that highlighted a five-run outburst. Second baseman Nick Madrigal, rightfielder Trevor Larnach and third baseman Michael Gretler each drove in three runs for Oregon State, which capitalized on two LSU errors and 12 walks issued by Tiger pitchers.
Oregon State took a 1-0 lead in the top of the first inning against Walker when centerfielder Steven Kwan singled, moved to second on Madrigal's groundout and scored on a single by Larnach.
The Beavers extended the lead to 3-0 in the fifth when Larnach delivered a two-out, two-RBI single against LSU reliever Caleb Gilbert. The runs were unearned as Oregon State was able to take advantage of an LSU error in the inning.
Oregon State widened the gap to 8-0 in the sixth when Madrigal provided an run-scoring groundout before Harrison unloaded a grand slam, his team-best ninth home run of the season.
The Beavers led 11-0 in the seventh when LSU scored on a solo homer by centerfielder Zach Watson, his ninth homer of the season and his fifth in NCAA Tournament games.