The Orioles were down 5-0 in early in the contest before staging a comeback, handing T.J. McFarland (4-1) a victory with an inning in relief of Chris Tillman.
The starter had yielded five runs (four earned) in five innings for the Orioles (85-77).
Rubby De La Rosa (0-2) took the loss for the American League East champion Bosox (97-65), who finished the regular season tied with St. Louis for the best record in the majors.
Quintin Berry smacked a two-run homer and Jacoby Ellsbury added a solo shot for Boston.
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