Eugenio Suárez homered to center field for Arizona (31-34) against his former team in the second. Corbin Carroll had an RBI single in the third.
Reds starter Brady Singer went five innings, allowing two runs and five hits. He struck out three and walked three, leaving with the score tied 2-all.
Taylor Rogers (2-2) pitched two hitless innings for the win, and Tony Santillan worked a scoreless ninth for his second save.
Gallen (4-8) gave up four runs and six hits in 6 2/3 innings. He struck out five and walked three.
Key moment: After Jake Fraley’s two-out single in the seventh, McLain lined his seventh homer of the season into the left-field seats to chase Gallen.
Key stat: Encarnacion-Strand homered in all three games of the series after coming off the injured list Friday. He had been out since April 17 with a lower back strain.