Lester (13-8) collected his third win in four starts, surrendering eight hits without a walk while striking out nine.
Will Middlebrooks erased a 1-0 deficit with a two-run single in the fifth, providing all of Boston's offense.
Scherzer (19-2) absorbed just his second loss of the season after giving up two runs on five hits in a seven-inning performance.
Julio Iglesias got the only RBI for AL Central-leading Detroit.
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