Coming in from the bullpen to a standing ovation from the sold-out crowd at Fenway Park, Gagne overpowered his first two batters Thursday in Boston's 7-4 victory over Baltimore.
It was the first appearance for the former Rangers closer since he agreed to a trade that relegated him to a setup role with the Red Sox.
"It was awesome," Gagne said. "I was a little nervous. But the adrenaline kicked in and the fans really got me going."
Doug Mirabelli went 3-for-3 with a homer, recovering from a baserunning gaffe to drive in the tiebreaking run in the seventh inning. Tim Wakefield (13-9) won his third consecutive start and sixth out of seven, allowing three runs and six hits in seven innings with a walk and five strikeouts.
With closer Jonathan Papelbon resting after his outing Wednesday night and lefty setup man Hideki Okajima needing just six pitches to get through the eighth, Gagne came on for the ninth. He threw seven consecutive pitches to strike out Kevin Millar and Miguel Tejada -- both looking.
Gagne lost his chance for a perfect debut when Aubrey Huff's popup landed between third baseman Mike Lowell and shortstop Alex Cora, then bounced into the stands for a double. Jay Payton singled through the hole on the right side to make it 7-4, but Gagne got Jay Gibbons on a fly ball to left to end the game.
Then the newest member of the Red Sox quickly untucked his shirt -- No. 83, the second-highest ever for the Red Sox -- and went through the traditional handshake line.
"I envision him pitching a lot of innings of importance," Red Sox manager Terry Francona said. "I thought it was a good time for his first. This guy's pitched a lot of games, but it was a nice way to get him in a Red Sox uniform."
Mirabelli had his first three-hit game since 2004, joining Eric Hinske in back-to-back homers in the fourth for a 3-0 lead. The Orioles tied it in the fifth off Wakefield and protected the tie when Mirabelli was thrown out at the plate in the sixth.
But Mirabelli singled off Rob Bell (3-2) to score Coco Crisp and spark a four-run seventh for Boston. Cora followed with an RBI single, and Dustin Pedroia added a two-run double off the glove of a diving Nick Markakis to make it 7-3.
"To go back and tag and try to come home like that was the second mistake and it's embarrassing," Mirabelli said. "I still feel like I had a terrible game. ... it's hard to face the team. It's hard to face everybody."
Bell started the seventh and got just two outs, allowing four runs, four hits and an intentional walk. Corey Patterson had two hits and a pair of RBI for Baltimore, which lost for the third time in 10 games and has dropped two straight for the first time since the All-Star break.
Boston loaded the bases off Jeremy Guthrie before Pedroia struck out ending the second, and again in the sixth when Markakis dropped Kevin Youkilis' fly ball near the right-field stands. David Ortiz followed with a long fly ball to right, but Mirabelli left third base early, went back to the bag, and then got thrown out easily at the plate for the final out of the inning.
Mirabelli, the personal catcher for Wakefield, was booed when he took the field to start the seventh.
- Manny Ramirez drove in the 1,585th run of his career, passing Rogers Hornsby and Harmon Killebrew and moving into 32nd place.
- Markakis' error was his first since last Aug. 15, a span of 148 games.
- RF J.D. Drew was a late scratch from the Boston lineup and replaced by Hinske. Drew ran for Hinske in the seventh.
- The Red Sox also shifted their rotation so Josh Beckett will start on Sunday and Curt Schilling will return from the DL on Monday.
- Wakefield has a decision in all 22 starts this season.