Infante's two-run blast in the fourth inning broke a 3-3 tie, putting the Tigers ahead to stay, and he added a run-scoring hit in the eighth to help seal the win.
Rick Porcello (1-2) notched his first victory the season, bouncing back from a rough start in his last outing when he yielded nine runs in less than inning against the Los Angeles Angels. The right-hander yielded three runs on five hits over 6 1/3 frames.
Jose Valverde picked up second save with two strikeouts in the ninth.
Braves starter Kris Medlen (1-3) was tagged for 10 hits over 5 1/3 innings, allowing five runs and a pair of walks while fanning three.
Justin Upton belted his MLB-best 12th homer for Atlanta, which lost for the sixth time in seven games.