The Schaumburg Boomers rallied from 3 runs down but allowed the host Rockford Aviators to rally in the eighth inning on their way to a 7-5 victory.
Rockford scored twice in the fourth inning to open a 2-0 edge and added 2 more in the sixth to go in front 4-1.
Schaumburg (28-20) struck for 3 runs in the seventh to tie the game. Chad Mozingo had a 2-run double, and Frank Pfister evened the game with a sacrifice fly.
The Boomers grabbed the lead in the eighth for the first time. Sean Mahley doubled to open the inning and scored on Alexi Colon's sacrifice fly.
Rockford was able to score 3 runs in the bottom half to regain the lead.
All-star starter Chris Phelan worked just 4 innings and allowed 2 runs. Devon Pearson suffered the loss. Mozingo and Mahley each had 2 hits.
The loss halted the Boomers' five-game winning streak. The rubber match of the series is Thursday at 7:05 p.m. Right-hander Mike Giovenco (4-4, 4.47) goes for the Boomers against righty Trevor Harden (2-4, 4.00).