Community scored first off Forrest starter Zach Brewer, beginning with Quinn Frost being hit by a Brewer pitch with one out.
After Brewer recorded a strikeout for the second out, Viking starting hurler Zeke Grissom helped his own cause with an RBI double that one-hopped off the right-field fence, scoring Frost.
Horvath took off for second moments later and the throw from the Vikings' catcher sailed into center field, allowing Harber to scoot home with the tying run.
The Unionville squad was undeterred, scoring on an RBI single by Justin Vassar in the top of the second to reclaim their one-run lead at 2-1.
Grissom did not allow any runs in the home half of the inning and Brewer came up with a 1-2-3 top of the third.
After a pop-up for the first out in the bottom of the inning, Horvath roped a triple to deep center.
Three consecutive walks to Brewer, Paten Pruitt, and Richard Hardin tied the game at 2-2.
Grissom recorded a strikeout for the second out of the inning before Blake Leonard was beaned by Grissom, bringing home Brewer with the go-ahead run.
Jacob Daughrity stepped to the dish and drilled a bases-clearing triple that broke the game open, giving Forrest a 6-2 lead.
Thaddeus Reyes followed with an infield single to score Daughrity and the Rockets took a 7-2 lead to the fourth inning where Brewer held firm, preserving the six-run lead.
The Rockets did not score in the bottom of the fourth off Grissom.
Community made it 7-3 on an RBI ground out by Tyler Christian that scored Frost, and after a pair of walks book-ended a Forrest error, freshman Tanner Garvin came to the hill in relief of Brewer with the bases jammed.
Garvin gave up a sacrifice fly RBI to J.D. Parker to make the score 7-4 before retiring Vassar on a grounder to Reyes to end the inning.
Community reliever Tom Nelson set the Rockets down in order in the home half of the frame and Garvin escaped a two-on, two-out jam in the sixth on a pop-up to Pruitt at first base.
FHS did not score in the bottom of the sixth and in the top of the seventh, Taylor Paschal and Parker banged a pair of one-out hits.
Garvin got the second out on a strikeout and the game ended on a hard line drive to Reyes at short.
Brewer picked up the win and Garvin recorded the save on the mound for the Rockets (2-7), who travel to Community (7-6) on Tuesday for back half of the home-and-home series.