BOSTON -- While Mike Carp would love to be an everyday player, he is more than comfortable playing in a reserve role.
He showed why Wednesday night.
Carp came off the bench in the eighth inning and drove in the eventual game-winning run, leading the Boston Red Sox to their fourth straight victory, a come-from-behind, 4-3 victory over the Baltimore Orioles.
"I couldn't be happier about the situation I'm in now," said Carp, one of the final players to make the team in spring training. "It's tough sometimes not getting the at-bats you want, but to be a part of this team and this clubhouse and the way we go out about our business every day, it's a dream team, a lot of fun and just a dream season altogether."
Dustin Pedroia tied the game with a two-out, two-run double in the seventh, John Lackey pitched into the eighth, and Jacoby Ellsbury had two hits and two stolen bases for the Red Sox, who won for the seventh time in their last 10 games. Boston maintained a 2 1/2-game lead over the Tampa Bay Rays for first place in the American League East.
Chris Davis hit his major-league-leading 47th home run of the season, and Manny Machado also went deep for the Orioles, who lost for the third time in four games to fall 7 1/2 games behind Boston.
"Tomorrow's another day, a chance to feel good about us going forward," Baltimore manager Buck Showalter said. "We came close tonight, and it's frustrating for our guys because I thought they deserved to win that game."
The Red Sox strung together a two-out rally against Tommy Hunter (3-3) in the eighth. Jarrod Saltalamacchia doubled off the Green Monster, and Stephen Drew was intentionally walked. Highly touted prospect Xander Bogaerts -- who was 0-for-3 in his Fenway Park debut -- was replaced by Carp, who answered the call with Boston's fourth go-ahead RBI by a pinch hitter this season, tied for the most in the AL.
Carp's flare barely sailed over the outstretched arm of third baseman Machado as Saltalamacchia scored.
"That's the job that was given to me at the beginning of spring," Carp said. "They told me when I came in, 'We see you as a bench player,' and that's the way it's played out all year.
"I've gotten stretches where I've had opportunities to play a little more than others, but that's my goal is to come in like tonight, have a big hit and win a ballgame."
Boston manager John Farrell isn't second-guessing the decision to keep Carp as a reserve.
"The versatility at the time, it came down to him and (Lyle) Overbay," Farrell said of the spring training battle. "Lyle has gone on to have a good year on his own part (after moving on to the New York Yankees), but Mike Carp in the role he's been in has thrived."
The Red Sox were held in check by Bud Norris until they broke through against Baltimore's bullpen in the seventh.
Francisco Rodriguez surrendered a leadoff double to Drew and a single to Ellsbury. Darren O'Day came in and got Shane Victorino to line out before yielding Pedroia's double that barely scored Ellsbury from second.
Lackey kept the Red Sox in the game by holding the Orioles to three runs on seven hits over 7 1/3 innings, striking out four and walking one.
Craig Breslow (4-2) pitched two-thirds of an inning for the win. Koji Uehara threw a perfect ninth for his 14th save in 17 opportunities.
One night after scoring 13 runs on 14 hits, Boston was silenced by Norris.
Acquired at the trade deadline from Houston, the right-hander surrendered one run on four hits over 5 1/3 innings with seven strikeouts and four walks.
"I think we underestimate how hard it is to pitch 5 1/3 innings on the road in the American League East at this time of year, so I'm going to take it as a positive," Showalter said. "He pitched well for us, gave us a chance to win. We had a rested bullpen, and we didn't get it done."
Baltimore took a 1-0 lead in the first when Machado beat out an infield single and scored on a double by Davis.
Machado then made it 2-0 in the third with his 12th homer of the year, belting an 0-1 offering from Lackey over the Monster.
The Red Sox cut the deficit in half in the bottom of the third on an RBI single by Victorino, who drove in a career-high seven runs Tuesday.
Davis led off the sixth with a solo shot to center, his fifth against Boston this season.
NOTES: Sean Collier, an MIT police officer who was killed in April, allegedly by the Boston Marathon bombing suspects, was honored during the ceremonial first pitch. Nine members of his family threw out pitches to Red Sox players. ... Boston RHP Clay Buchholz, on the 60-day disabled list with a neck strain, will make his second rehab start Friday for Triple-A Pawtucket. He will throw 50 to 55 pitches before possibly returning to Boston to rejoin the rotation, according to Farrell. ... Baltimore RHP Chris Tillman (14-4, 3.66) will face Boston LHP Jon Lester (12-7, 3.97) Thursday in the finale of the three-game series. ... In need of a reliever, Baltimore called up RHP Kevin Gausman and sent LHP Wei-Yin Chen to the rookie-level Gulf Coast League. Showalter said Chen, who was tagged for eight runs over 3 2/3 innings in the worst start of his career Tuesday, will return to the majors and pitch Sunday against the Yankees.