Oregon State seventh inning - Tyler Malone walked and stole second. Grenier bunted for a sacrifice out, and the runners moved to second and third. Gretler was hit by a pitch.
Fehmel (6-2) wiggled out of a mini jam in the fifth before Zach Watson's homer in the seventh allowed LSU to avoid getting shut out for the first time in its 62 CWS games.
Monday he did exactly what Oregon State needed him to do.
The Beavers concluded the five-run sixth with an 8-0 lead and added five more runs over the next two innings. LSU's Kramer Robertson is one of the surest hitters in the game. With one on and one out, second baseman Nick Madrigal hit a single and went to second base on a throwing error.
Then Heimlich, 11-1 with a 0.76 ERA in, was gone, removing himself from competition after The Oregonian newspaper published a report that he was convicted of child molestation in 2012. The victor of Wednesday's game would have to defeat Oregon State on both Friday and Saturday in order to advance to the CWS Championship Finals.
In the fifth, Larnach drove in two more runs off reliever Caleb Gilbert by floating a breaking pitch into shallow center field to score Grenier and Madrigal on unearned runs, standing at first with a wide-eyed smile.
Fehmel's performance was slightly lost in the midst of the Beavers' scoring output which is a shame because this kid is big time. He singled in the second and accounted for LSU's only run with his ninth homer of the year in the seventh. The 12-run margin tied the largest in a CWS game in the seven years it's been played at TD Ameritrade.
The 6th inning is where the Beavers took the reigns of this game and never looked back. For some batters, he started off with a fast ball.
The Titans are traditionally a "small-ball" team that would seem to be a good fit for pitcher friendly TD Ameritrade Park.
"We talked before the game about this is our time, this is our opportunity, this is what we came here for and let's not miss that moment", said Oregon State coach Pat Casey".
It was an absolute massacre, one of the Tigers' worst defeat margins in 18 CWS trips. Watson hit into a game-ending double play.Two Tigers players were thrown out on the bases. Walks off the mound after a visit from the dugout, apparently injured, with a 2-2 count on the first batter of the third inning.
OSU struck quickly in the top of the first. Should they win that contest, they will be in the final 3-game series over the weekend.
Walker, who didn't pitch in the super regionals, experienced similar tightness following a 75-pitch simulated game last week. Walker threw this past Saturday and had no discomfort. Bush was lifted after walking the leadoff batter in the sixth.
Sophomore outfielder Jackson Lueck is batting.319 for FSU with nine homers and 54 RBI, while junior infielder Dylan Busby is hitting.316 with 21 doubles, 65 RBI and a team-best 15 home runs.
Martin was credited with the five earned runs and couldn't match his counterpart, Brendan McKay. Fehmel's line: Eight innings, two hits, one run.
Oregon State scored 10 runs with two outs and made LSU pitcher pay for 12 walks.
LSU, which had its seventeen game hitting streak snapped, will face elimination Wednesday in a rematch with Florida State, which eliminated Cal State Fullerton earlier in the day.
Oregon State's Bryce Fehmel led the dismantling of LSU's 17-game winning streak.
Coach Paul Mainieri's comments: "It was a hard night for the Tigers".
"The main thing was keeping them off-balance as best I could", Fehmel said. "It (the grand slam) was kind of a momentum shifter".
An inning later, Oregon State took advantage of some more free bases to break the game open.