A grand slam by Alberth Martinez in the eighth inning turned a 5-3 deficit into a 7-5 lead, and Fort Wayne held on in the ninth to take down Clinton.
The TinCaps (14-10) won their fourth home series this month and moved to 10-3 at Parkview Field after the late-inning blast by Martinez.
The LumberKings (11-12) scored four early runs on Fort Wayne starter Walker Weickel and looked to be cruising toward a series win. But a run in the fourth inning and two in the fifth kept the game close enough for Martinez to put the TinCaps over the top.
It was the second home run in two games for the left fielder, who had a solo shot in a 6-2 loss Monday. This one meant a lot more.
After an out to start the inning, Jeremy Baltz singled to right, and Gabriel Quintana earned a walk. A strikeout by Luis Tejada put Fort Wayne in a poor position, but Corey Adamson drew another walk and Martinez changed the complexion of the game with one swing of the bat.
Roman Madrid came on in the top of the ninth to close the game and earn his fifth save of the season.
Fort Wayne hits the road for a six-game stretch Wednesday. The TinCaps will face the Burlington Bees at 7:30 p.m.