LSU (11-1) loaded the bases with one out in the ninth, but Princeton left-hander David Palms retired the next two batters to earn a save and preserve his squad's first victory of the season.
Princeton southpaw Michael Fagan (1-0) was credited with the victory as he allowed five earned runs on one hit and five walks in 3.1 innings. LSU right-hander Ben Alsup (2-1) was charged with the loss as the senior surrendered three earned runs on two hits and four walks in 4.2 innings.
First baseman Alex Edward had two hits, including a double, and a pair of RBI to lead the Tigers at the plate. Designated hitter Raph Rhymes also collected two hits, while shortstop Austin Nola delivered a pair of RBI.
"It's a painful loss, and we just dug ourselves too deep of a hole," said LSU coach Paul Mainieri. "I felt very good about the way we prepared for this game, but we didn't execute as well as we should have. Princeton outplayed us and deserved to win the game; they have a great coach and they did a great job today.
"At the same time, I was very proud of the way our guys battled back and nearly earned a win. We have a great group of kids who work very hard and they care about the right things. We'll give them a day off Monday, and I know they'll be ready to go next week."
Princeton notched a run in the top of the third to take an early 1-0 lead. However, Nola hit a sacrifice fly to right field to score Rhymes from third and tie it at 1-1 in the bottom of the frame.
The opposing Tigers plated three runs in the top of the fifth to regain a 4-1 advantage highlighted by a two-run double from first baseman Mike Ford.
Princeton added three more runs in the sixth to go up, 7-1. Center fielder Nate Baird drove in his second and third runs of the game on a two-run single to left center, and right fielder John Mishu followed two batters later with his own RBI base hit.
The Ivy Leaguers pushed another run across in the eighth when shortstop Matt Bowman drove in second baseman Alex Flink on a sacrifice fly to center.
LSU erupted for six runs in the bottom of the eighth to cut Princeton's lead to 8-7. With the bases loaded, Nola drew a walk to bring home a run, and right fielder Mason Katz drove in another on an RBI single in the next at bat.
Edward then followed with a two-run double down the left field line, and pinch-hitter Mike Lowery provided an RBI grounder to second. Second baseman Jacoby Jones capped the big inning with a base hit to right to score Edward.
After back-to-back walks by third baseman Tyler Hanover and Mahtook, a sacrifice bunt from Nola and an intentional pass to Katz, the Tigers had the bases loaded with one out in the bottom of the ninth. However, Palms got Edward to pop out and caught pinch-hitter Jackson Slaid looking on a 3-2 count to end the rally.