Tigers Manager Jim Leyland elected to intentionally walk Kevin Youkilis to load the bases and Ortiz responded by blasting a pitch into the left-center field gap, scoring all three runners and giving the Red Sox a walk-off win.
Boston's rally evened its three-game series with Detroit at one victory apiece and made a winner of Hideki Okajima (4-3) for throwing one scoreless frame.
Miguel Cabrera belted his 26th home run of the season for the Tigers, who have lost five of their last six games.
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