Savannah scored twice with two outs in its final at-bat off Tyler Mizenko (1-4) in the seven-inning opener. Cole Frenzel had the game-winning hit, a single to left that scored Stefan Sabol.
Shawn Payne homered for the GreenJackets.
In the nightcap, Savannah pitcher Matthew Koch (6-4) allowed just one hit, a triple to left by Payne leading off the seventh and final inning. Payne scored on a sacrifice fly by Trevor Brown.
Frenzel had two hits and two RBI to lead the Sand Gnats.
Justin Schumer (3-7) took the loss.