Steve Pearce reached base four times (three singles and a walk) and had three RBI: the go-ahead run that snapped a 1-1 tie in the fifth and two insurance runs in the sixth.
Rick Porcello (5-2-1-1-5, 100) threw 32 pitches in the second inning and 25 in the third, which led to his early exit.
In addition to their eight hits, the Red Sox also drew nine walks.
Atlanta led 1-0 when Kirk Suzuki homered with two outs in the bottom of the second. (But all that meant was the Red Sox would snag their 42nd come-from-behind victory.