BALTIMORE -- Arm by arm and inning by inning, the bullpen got less crowded. Baltimore cycled through nearly all of its relief arms Wednesday night, when it used seven relievers to try to hold a scoreless tie. The deadlock held until the 12th inning, when southpaw Kurt Birkins gave up a grand slam in a game the Tigers eventually won, 4-1.

Detroit's Craig Monroe came through with the game's biggest hit, a two-out slam that traveled over the fence in straightaway center field. The inning had been extended by an infield hit and a walk, which heightened the drama around Monroe's at-bat. Prior to that hit, the two teams had combined to leave 23 runners on base.

"I got in there, which was the important thing," Birkins said of his season debut. "I got my feet wet, although I could've hoped for something a little bit better. I threw strikes, and that's what I wanted to do. I don't want to walk guys and get guys on base. I threw one too many changeups, I guess, and left it a little bit up. He's not going to let that go."

Baltimore manager Sam Perlozzo ran through virtually everyone in the 'pen Wednesday night, but he made sure not to overburden any particular reliever. Everyone -- from John Parrish in the sixth inning to closer Chris Ray in the ninth and Birkins in the 12th -- pitched one full inning and left before reaching their maximum pitch count.

Still, if the game had gone much longer, Baltimore may have been caught with an empty bench. The Orioles (3-6) used seven relievers Wednesday, and their eighth -- long man Jeremy Guthrie -- had pitched three innings the night before. The O's also used two of their three bench players, leaving just backup catcher Alberto Castillo.

In all, Baltimore's relief staff worked seven innings and allowed just six hits -- four of them given up by Birkins.

"I felt pretty comfortable with where we were in the ballgame with our bullpen. I didn't expect it to go as far as it went, but they all did pretty good jobs," Perlozzo said. "They hadn't pitched, and they pitched one inning apiece. If you can pitch them one inning, you can do that three days in a row. They should all be fine."

Baltimore starter Adam Loewen only was able to work five innings, and he steadily fought his control throughout the breezy night. The southpaw gave up five hits and walked four batters, but he stranded runners in each of his innings. Loewen worked out of a bases-loaded jam in the fifth inning and left the scoreless game after throwing 95 pitches.

Detroit's Justin Verlander lasted two innings longer than his Baltimore counterpart. The right-hander allowed just three hits and rarely was challenged after the second, when he escaped with the bases loaded. The Orioles only had three baserunners after the second against Verlander, and he stranded two of them in scoring position.

"I got myself in some trouble," said Loewen, "but I could tell from the beginning of the game that Verlander was on. I couldn't really give them anything to hit, so that's the mentality I took into it. I think I did my job."

"We knew we were going to be in a pitchers' duel in the beginning," added Perlozzo. "I thought Adam was just a little bit erratic in the strike zone, but he made good pitches when he had to. He just got his pitch count up."

Baltimore's best late chances to score came in the eighth and the 11th innings. The Orioles drew a one-out walk in the former rally, and a fielding error by third baseman Brandon Inge helped advance the runner. Baltimore had two chances to score, but reliever Fernando Rodney extinguished the threat with a popup and a strikeout.

The Orioles threatened again in the 11th, when first baseman Aubrey Huff singled with one out. Baltimore pinch-ran for him with utility man Freddie Bynum, and one out later, designated hitter Kevin Millar lifted a long fly ball to left field. That ball dropped right by the warning track, perhaps knocked down by the persistent windy conditions.

"It was tough watching Millar hit that ball five feet away from being a walk-off," Loewen said. "Everybody jumped up. ... We really worked hard in this game. We didn't give up -- even when they went ahead in the 12th."

Detroit (5-3) worked hard against Birkins in the 12th, starting things off with a leadoff single by catcher Ivan Rodriguez. Birkins got fly balls from the next two batters, but Magglio Ordonez hit an infield single. Shortstop Carlos Guillen walked after a hard-fought at-bat, and Monroe won the game on a 1-1 pitch.

Perlozzo said Guthrie was capable of throwing one inning, but Birkins likely was in until the game was decided. The end came nearly four hours after the beginning, and after nearly all of the crowd went home. Baltimore started with 13,288 fans in attendance at Camden Yards, which was the second-smallest crowd in the park's history.

"Out in the bullpen, we were talking about how long it was going to go. It's one of those things," Birkins said. "You've got to keep your focus even though you're out there so long. ... Me and Jeremy were the only guys left out there, and we were just trying our best to stay warm, stay in the game and stay focused."