The TinCaps battled back from a two-run deficit in the eighth to set up a game-winning hit by Alberth Martinez in the bottom of the ninth for a 6-5 victory.
Fort Wayne (17-13) avoided its first four-game losing streak of the season after a five-run seventh inning by Great Lakes (12-19) nearly cost the TinCaps the game. Starter Joe Ross gave up four hits and five runs the seventh after a two-hit, no-run outing through six innings.
But Fort Wayne covered for him in the eighth, with a triple by Luis Tejada scored Jeremy Baltz and Gabriel Quintana.
Brian Adams scored the winning run on a grounder to third. He barreled toward home on the play, and the ball reached the catcher just as he got to home, but was dropped.
The victory was Fort Wayne's third walk-off of the season at Parkview Field. The TinCaps will take on the Loons again Thursday at 7:05 p.m.