Dobbs' third-inning double erased a 3-2 deficit and he scored an insurance run off Ricky Nolasco's single.
Nolasco (2-0) picked up the win after giving up three runs and eight hits and walking three in 5 1/3 innings. The Miami bullpen, however, didn't give up a hit or a walk over 3 2/3 innings. Heath Bell, the sixth Marlins pitcher Thursday, pitched the ninth for his second save.
All of the Miami runs came off Cubs starter Jeff Samardzija (2-1). He allowed eight hits, walked five and struck out three in 3 2/3 innings. The Marlins got only one hit off the Chicago bullpen.
Logan Morrison singled in a run and scored another in the Miami first but Chicago's Bryan LaHair doubled into the right-field corner with the bases loaded in the third to put the Cubs up 3-2.
Dobbs answered with a shot into the left-field corner that drove in a pair of runs and then scored on Nolasco's hit in the bottom of the inning.