Joaquin Arias led off the ninth against Cincinnati closer Sean Marshall (0-2) with a walk, and Ryan Theriot followed with a single. After pinch-hitter Brett Pill struck out, Pagan lofted a 1-2 pitch 386 feet into the left field seats to snap the Giants' losing streak in Cincinnati at seven games.
Javier Lopez (2-0) allowed two hits but no runs in the eighth to earn the win. Santiago Casilla struck out the side in the ninth for his second save in two opportunities.
