A three-run Andrew Benintendi homer broke open a tight game in an eventual 5-1 Boston win at Baltimore Wednesday night.
The win was the third in a row in the series pitting AL East leaders for the Red Sox (88-64), who now have a magic number of six to clinch the division.
Baltimore (82-70), losers of five of seven, have a one-game lead on Detroit and Houston for the second AL wild-card spot.
Clay Buchholz (8-10, 5.00 ERA, 1.37 WHIP) got the win, giving up a run on three hits in seven innings, striking out four and walking two.
Ubaldo Jimenez (7-12, 5.71 ERA, 1.61 WHIP) was the tough-luck loser, giving up two runs, neither earned, in five and a third innings, striking out eight and walking four.