Tied at one in the bottom of the 11th inning, reliever Ryan Brasier delivered a pitch to Trey Mancini that was taken for a ride to centerfield.
However, the deep fly ball didn't end the game like it appeared it was destined to do, because Boston centerfielder Jackie Bradley Jr. had other plans. He leaped, reached over the wall and caught what would've been a walkoff home run.
In the top of the 12th, Andrew Benintendi blasted a solo homer for the Red Sox and gave them a 2-1 lead.
Heath Hembree than retired the Orioles in order to secure the victory.
The win moved Boston to 19-19 on the season while Baltimore dropped to 13-24.