LEXINGTON, Ky. — Trailing by two runs, with one out and the bases loaded in the bottom of the eighth inning, Kentucky fifth-year senior catcher Marcus Nidiffer — in the final at-bat of his home career — connected on a 3-2 offering from LSU All-American closer Matty Ott, sending the ball soaring over the left-field fence for the game-winning grand slam, with UK sweeping the 20th-ranked Tigers for the first time in 19 years with a 6-4 win Sunday afternoon at Cliff Hagan Stadium.

Nidiffer came to the plate with one out, the bases juiced and Ott on the mound for the Tigers — the defending national champions owning a two-run lead. The native of Bristol, Tenn., worked the count full before connecting on his 10th home run of the season. The sweep was just the second sweep over LSU in the history of the program and the first sweep since UK won three games against the Tigers in 1991 in Lexington.

“He’s going to be remembered forever for that,” UK head coach Gary Henderson said. “He’ll be 45 years old telling his little-league team about that grand slam he hit against LSU to complete the sweep.”

With UK trailing by two runs entering the bottom of the eighth inning and with LSU starting pitcher Austin Ross working on a gem, Kentucky All-American leadoff hitter Chris Bisson reached on a two-strike, swinging bunt, hit back to Ross on the first-base line. Ross attempted to tag Bisson and when he missed the tag, attempted an off-balance toss to first to get Bisson, with the throw sailing high for a throwing error.

Sophomore Chad Wright then drew a walk to end the night for Ross and bring LSU ace reliever Paul Bertuccini in the game.

Senior Gunner Glad’s second sacrifice bunt of the season moved both runners into scoring position, with LSU calling on hard-throwing lefty Zach LaSuzzo to face left-handed hitter Lance Ray with one out and runners on second and third base.

LaSuzzo threw one pitch, plunking Ray with a fastball, loading the bases for Nidiffer and bringing Ott out of the bullpen. Ott, the Southeastern Conference saves leader and owner of 27 career saves in his two-year career, issued two balls to Nidiffer to start the at-bat, then got a strike, threw another ball and got Nidffer to swing through a pitch to make the count full. With the count at 3-2, Nidiffer fouled off an offering from Ott and on the next pitch, belted his 10th homer of the year.

Kentucky (29-23, 12-15 SEC) entered the weekend series with the defending NCAA champions two games out of the eighth spot in the conference, needing to finish the last two remaining conference weekends strong to secure a berth in the 2010 SEC Tournament, set for May 26-30 at Regions Park in Hoover, Ala.

Kentucky, Tennessee and LSU are in a three-way tie for seventh in the SEC with 12-15 records.

If all three teams finish the season with the same record, Kentucky would be the No. 7 seed in the SEC Tournament and LSU would be the No. 8 seed due to the head-to-head tiebreakers.