After five innings of Chris Tillman, Showalter needed Miller to face the Tigers' murderers' row of Miguel Cabrera, Victor Martinez and J.D. Martinez with a one-run lead in the sixth.
"We've talked to them since the season was over about how this was going to work," Showalter said. "There aren't guys strolling down there after the fifth inning, like some of them do. The way we have normally used them, they know that it's all hands on deck."
The trio -- all of whom homered on Thursday -- could all attack the left-handed Miller from the right side of the plate. Miller took caution with Cabrera, walking him on a full count. Next up was Victor Martinez, who entered the day hitless in two career at-bats against Miller. The towering reliever danced a slider under the designated hitter's bat to fan him for the second time in the game. Martinez hadn't struck out twice in one game since July 18.
"It's no-holds-barred in the postseason," O'Day said. "Buck once again did a good job of managing the bullpen and getting them in there when he thought it was a good matchup."
Miller hadn't pitched before the seventh inning since being traded to Baltimore and hadn't thrown more than 1 1/3 innings since Aug. 28. But in his first postseason game -- he missed Boston's World Series run last year with a left foot injury -- Showalter not only used Miller in an unfamiliar spot, he stretched him out, too. Miller got the final out of the sixth and the first two in the seventh before handing the ball to O'Day, who coaxed a Rajai Davis groundout to end the frame.
"This is a situation where we're going to be called on to get more outs," said Miller, who expects to be available for Game 2 on Friday. "It's win at all costs, and however you get to the finish line, you just want to make it there."
O'Day got the first two outs on a double-play ball in the eighth before surrendering a home run to Cabrera and being replaced by closer Zach Britton. Britton got Victor Martinez to ground out to end the inning, and then the Orioles erupted for eight runs in the eighth.
That enabled Showalter to take out Britton in what would have been a four-out save situation into a low-leverage ninth for Tommy Hunter, who put the finishing touches on the Game 1 win.
David Wilson is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.