The Red Sox split a day/night doubleheader with the O's on Monday, dropping the first game 6-5, before exploding in the nightcap for an 18-9 win.
"It was a well-needed win," said Boston catcher Jason Varitek.
Boston held a nine-game lead on the Tampa Bay Rays early in September, but has seen that advantage dwindled down to just two games, as the Red Sox have won just five of their 19 games played this month.
"At this point, we just need wins," said infielder Jed Lowrie, who belted a three-run homer. "We don't need anything else. It was a big win and we've just got to use the momentum from tonight and carry it into tomorrow and the rest of the year."
Boston, which dropped three of four over the weekend to the Rays, is also five games back of the New York Yankees in the American League East with a three- game set against its hated rivals on tap for this weekend.
"It's a nice win and we control our own destiny at this point," said Jacoby Ellsbury, who hit an inside the park home run as part of seven-run seventh inning in Monday's game two. "So we know if we go out and play baseball like we can, we'll be in good shape."
Bedard goes tonight in his first start since September 3. The oft-injured left-hander, who pitched for Baltimore from 2002-07, has been sidelined with a lat strain.
He is 5-9 on the year with a 3.50 ERA, but hasn't lasted longer than six innings in any of his six starts since joining Boston in a seven-player deal with Seattle at the July 31 trade deadline. Bedard's 1-2 with a 3.66 ERA with the Red Sox.
Baltimore, meanwhile, will counter with Rick VandenHurk, who has given up four runs in six innings of work this season. This will also be his first-ever start against the Red Sox.
Boston has handled the Orioles all season, going 9-4 against them, including a 6-1 mark in Beantown.