Heyward's first homer of the season off Kyle Lohse (0-1) put the Braves on top 2-1 in the fifth and snapped a string of 22 scoreless innings against the Brewers.
Freeman opened the sixth with his first homer and added a two-out home run in the eighth to make it 4-1.
Wood (1-0) settled down after allowing a home run to Carlos Gomez on his first pitch. The left-hander allowed one run on five hits in seven innings. Craig Kimbrel struck out the side in the ninth for the save.
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