The Red Sox were down 5-2 in the sixth when they scored three times to forge a tie. David Ortiz began the comeback with solo homer and Middlebrooks, who had singled, scored the equalizer on a Tommy Hunter's balk.
Dustin Pedroia drove in a pair of runs for the Bosox, who won the first of a three-game set at Camden Yards.
Chris Davis knocked a solo homer for the American League East-leading O's.
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