Rizzo, a highly touted hitting prospect obtained in a trade with San Diego last winter, came to bat with two runners on and two outs in the fourth inning and the score tied 3-3. He ripped a 2-2 pitch into the center field to score Steve Clevenger with the go-ahead tally and also added a single to finish 2-for-4 in his first game with the Cubs.
Luis Valbuena and Darwin Barney each chipped in with two hits and an RBI as Chicago took the opener of a three-game series.
Mets starter Dillon Gee (5-6) surrendered four runs on nine hits in a five-inning stint.
Gee, David Wright and Josh Thole each drove in a run for New York.