Then, with Maxwell at third and Randy Choate on the mound, it seemed the rally would come to an end when Brian Bogusevic lofted a routine fly ball to left. But the ball popped out of Morrison's glove, allowing the go-ahead run to score.
Brett Myers made the lead hold up with a 1-2-3 bottom of the ninth, earning his second save of the year and snapping the Astros' three-game skid.
Rhiner Cruz (1-0) earned his first major league win with scoreless innings of one-hit ball in relief.
Morrison had two RBI for the Marlins.
Carlos Zambrano started for Miami and surrendered just one run on four hits while issuing six walks.
Google buys drone maker Titan Aerospace
Pistorius testifies he didn't consciously pull trigger when he shot girlfriend