Lartigue's blast came after UK closer Sean Hjelle (4-1) surrendered a one-out double to Tate Blackman and issued a walk to J.B. Woodman.
It capped a day which saw the Cats blow a 5-0 lead and waste another strong pitching effort by Kyle Cody, who allowed only one earned run over 6.2 innings on the mound. The senior right-hander scattered seven hits, walked only one and struck out seven.
Kentucky (29-23, 13-14 SEC) got a two-run homer from Tristan Pompey in the second inning and a three-run shot from JaVon Shelby -- his SEC-leading 12th of the season -- in the third inning, but could not hang on to the lead. An error and a passed ball helped the Rebels plate two runs in the fifth. Another error and a wild pitch gave them another run in the seventh.
Blackman had three hits to lead Ole Miss (39-13, 17-10). Holt Perdzock, Woodman and Lartigue each added two, including a solo home run for Woodman.
The Cats return to action Tuesday against Murray State in Paducah, Ky., before wrapping up SEC play next weekend at home against Missouri. They may need a sweep of the Tigers in order to keep a precarious spot in the NCAA Tournament. UK was slated as a No. 3 seed in the Louisville region prior to the weekend sweep in Oxford.