Florida State took the lead four minutes into the game when Dylan Busby drilled a ball over the center field fence of TD Ameritrade Park for a two-run homer.
Earlier in the afternoon, Cal State Fullerton and Oregon State met for a battle that ended 6-5 in the Beavers' favor, thanks in large part to Oregon State's defense pulling through on a pair of spectacular defensive plays that prevented certain Titans base-running shenanigans.
Walker started the games where LSU won the SEC West, the conference tournament and the regional championship, but missed his turn in the super regional when LSU swept Mississippi State in two games.
Duplantis made it all the way to third on the play, which made for an easy trot home after Greg Deichmann singled into right field.
Scoring more runs than the other team hasn't been an issue for LSU over the last month. Freeman scored when Wells made a bad throw to second base.
Lange is 4-0 in his last five starts with a 2.21 ERA, and he has limited opponents to nine earned runs on 28 hits in 36.2 innings with 12 walks and 43 strikeouts.
The double-elimination tournament features two brackets, and Sunday's games were the first in the second one.
Poche' was a viable option for relief against a Florida State lineup that has four switch hitters who are better from the left side.
Lackey deals, Rizzo leads offense as Cubs beat Pirates 7-1
"I respect the umpires and I never like to criticize them because I know they give their very best, but they got that one wrong". C Chris Stewart was reinstated from the 10-day disabled list and C Jacob Stallings was optioned to Triple-A Indianapolis.
LSU, the NCAA Tournament No. 4 National Seed, will play No. 1 National Seed Oregon State (55-4), a 6-5 victor Saturday over Cal State Fullerton, in a winners' bracket game at 6 p.m. CT Monday.
Poche' was not able to finish the game, turning it over to freshman Zack Hess with two outs.
It was the 22nd straight victory for No. 1 national seed OSU (55-4), which will continue CWS play at 4:05 p.m. Monday against fourth-seeded LSU (49-17).
Coach Paul Mainieri's comments: "It was a little bit of a weird game. And I think you'll see a team play a lot better".
Poche' allowed two hits and did not walk a batter in 2.2 scoreless innings.
After Alex Lange's first pitch to Florida State's Taylor Walls, the ball was taken out of play. That matches Scott Schultz for the most in LSU history, a record that has stood for 22 years.
LSU cut the deficit in half in the bottom of the inning. "That's one thing that has continued to stand out for me is how they stand up for one another and how they feel about one another". "But I never look back on the season and say, 'That was a failure.' Because it's so hard to get to this point". "You just got to kind of approach it like that". "I had to make the ideal throw or else the ball gets away and a run scores".
In the fifth, Walls drew a leadoff walk and set an FSU record by reaching base in 14 straight plate appearances. "Ever since the roster limits and changed bats, I think you have to have guys who can run and you need some athletes out there", Mainieri said. But unless the Seminoles can do the unthinkable, they and their fans will get an unpleasant reminder of how cold Omaha can be - even in the middle of June. All inning and probably earlier, Mainieri was thinking of a possible Watson-Busby, right-hander vs. right-hander duel in the ninth, though the ESPN announcers were saying Mainieri would go to right-handed closer Hunter Newman.