BALTIMORE -- As the ball left Mitch Garver’s bat, Leody Taveras -- standing on third base after a leadoff walk -- immediately threw his hands in the air. Marcus Semien, on second base after a walk of his own, barely even paused before celebrating. 

And at the plate, Garver dropped his bat well before the ball landed in the crowd before beginning his home run trot.

Garver, making his postseason debut at designated hitter for the Rangers, delivered in a big spot with a 419-foot grand slam deep over the left-field wall in the third inning, giving Texas an early 9-2 lead in an eventual 11-8 win over the Orioles at Camden Yards to go up 2-0 in the American League Division Series.

It was just the second postseason grand slam in Rangers history, joining Nelson Cruz’s walk-off in the 11th inning in Game 2 of the 2011 ALCS against Detroit.

“These playoff games, one swing can change it,” Garver said. “And I got into a situation there in the hitter's count where I was looking for the fastball and I was able to get it. And I think it's just a big momentum push for our whole team. And we needed all those runs today.”

Only 33 home runs went over the left-field wall at Camden Yards this season, good for the fewest in any MLB ballpark. Garver’s grand slam -- which was his fifth-hardest-hit home run of the year -- would have been a homer in all 30 ballparks, making it his eighth no-doubter this season.

“Left field here is so deep, but when he hit it, I knew it was gone,” Semien joked. “That just tells you how hard he hit it.”

• Rangers staying resilient away from home in postseason

Rangers manager Bruce Bochy has rotated a number of players through the three-hole in recent weeks, to no avail. Texas three-hole hitters had a .143 average through three postseason games entering Game 2 of the ALDS on Sunday.

Enter Garver, who slashed .270/.370/.500 in 87 regular-season games, but had yet to appear in the postseason before Sunday.

“I got a good pitch to hit, honestly,” Garver told FS1’s Ken Rosenthal in an in-game interview. “I was a little hesitant on the first pitch. I was kind of looking for the slider. Wasn't quite where I wanted it. Worked myself into a count where I could get a fastball. I had a feeling he wasn't going to go offspeed in a 3-1 count with the bases loaded, so I took my shot.”

Garver's five RBIs tied the Rangers' postseason single-game record, done twice previously: Cruz in the 2011 ALCS and Michael Young in Game 6 of the same series.

Eleven runs is the second-most the Rangers have scored in a postseason game in franchise history, with the most being 15 in Game 6 of the 2011 ALCS against Detroit.

“He came up big earlier, too, with that swinging bunt, speed showed up there,” Bochy said. “He can hit. He's done a great job this year for us, so I gave him a start today. He got a pitch he can handle, and he's got big power. It was big at that point in the game. Really it was the difference in the game.”

The Orioles took an early 2-0 lead over the Rangers, tagging starter Jordan Montgomery with three hits and a walk in the first inning. But Texas punched back with a five-spot in the top of the second inning before Garver broke it open with his grand slam in the third.

Garver said controlling the strike zone, limiting chase and driving the ball to all fields was key to the Rangers’ offensive approach in the win. 

“I think yesterday, not all of us, but a lot of us felt the moment was pretty big,” Semien added. “We were a little more swing heavy yesterday. Today, we knew the environment. We understood that we're not going to score a lot of runs doing what we did yesterday. Yes, we won the game, but let's try and control the strike zone a little bit more, make it hard on this young pitcher. We definitely did that.”

The Rangers took 11 walks, the most in a postseason game in franchise history and just the 10th time any team has walked 11 or more times in a game in postseason history. Corey Seager's five walks set a record for the most by one player in an AL/NL postseason game.

• Rangers' patience a detriment to Orioles in Game 2

“It's a pretty relentless attack,” Semien said. “You have to beat us in the strike zone. We didn't expand too much. The biggest thing in the postseason is putting the ball in play, working counts and swinging at good pitches. I think we did that the first two games, and we need to continue that heading into Texas. And we just have a really, really good approach, one through nine.”

Now after an 11-game, 14-day road trip, the Rangers will head back to Arlington with a 2-0 lead in the series and one win away from their first trip to the American League Championship Series since 2011.

“We've been on the road for a long time,” Semien said. “I think overall, we've been playing good baseball at home, and now we have an even bigger crowd behind us. It’ll be fun.”