Kaz Matsui connected for his third homer of the season after Cincinnati starter Ramon Ortiz (1-2) held the Mets scoreless through six innings.
Doug Mientkiewicz singled with one out in the seventh and after David Wright flied out, Matsui hit Ortiz's 1-1 pitch an estimated 385 feet over the right-field wall to turn the game.
Kazuhisa Ishii pitched 6 and 1/3 innings, giving up just one run and three hits to keep the Mets in the game.
Braden Looper saved the Mets 2-1 win in the ninth.
Matsui Hits Home Run In 2-1 Win Over The Reds