BALTIMORE — The meaningful September baseball the Yankees are thrilled (and maybe a tad surprised) to be playing did not get off to a good start.

It’s hard to imagine it being a much worse start, actually.

Rookie righthander Chad Green struggled early and left after 1 2⁄3 innings Friday night with an elbow injury. And the Orioles, who entered the game with an MLB-best 209 home runs, increased that total by four in pummeling the Yankees, 8-0, in front of 24,226 at Camden Yards.

Green, who will have an MRI on Saturday in Baltimore, said “I’d be lying if I said I wasn’t” thinking the worst regarding possible Tommy John surgery, but he added, “I’m hoping it’s nothing serious.”

Mark Trumbo hit his 41st home run and Chris Davis and Manny Machado each hit No. 33 for the Orioles, who also got No. 20 from Pedro Alvarez.

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Davis, who hit a two-run blast, and Trumbo went back-to-back against Nick Goody to complete a six-run second inning that gave Dylan Bundy, who had allowed five runs in two of his previous three starts, a cushion.

The Yankees (69-64), who had won their previous four series to climb back into the American League wild-card race, fell 3 1⁄2 games behind the Orioles and Tigers (both 73-61) for the second wild card. They managed only two hits against Bundy (8-5) and three relievers and didn’t get a hit after the third inning.

“It’s really unfortunate,” Girardi said of both the loss of Green and the loss to the Orioles. “It’s not what we needed, but you have to overcome it and move on . . . It’s one game and you can’t make too much of it, but [Saturday night’s] game is really important.”

Of more immediate concern is the condition of Green. The 25-year-old, 1-1 with a 3.54 ERA in his previous four starts, labored through 27 pitches in a scoreless first inning, then was charged with four runs in the second, an inning in which the Orioles hit three homers in taking a 6-0 lead.

After Green (2-4) walked Machado for the second time, shortstop Didi Gregorius noticed something and signaled to the dugout. Green departed after a brief conference with Girardi and trainer Steve Donohue.

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“It was just starting to tighten up and just something I thought was uncomfortable,” Green said. “Didn’t want to take any chances on it.”

Girardi indicated that Luis Severino, a Sept. 1 call-up who pitched one inning of relief Friday night, and Bryan Mitchell, recently back from injury and in the minors, are options to take Green’s rotation spot.

After relieving Green, Goody — who was among six players called up Friday as big-league rosters expanded — immediately allowed a two-run homer by Davis and a solo shot by Trumbo on a 0-and-2 pitch. Machado’s two-run homer off Kirby Yates in the fourth made it 8-0.

Alvarez’s blast over the rightfield wall and onto Eutaw Street earlier in the inning gave the Orioles six players with at least 20 homers, the 19th team in MLB history to achieve that. The 2010 Blue Jays were the most recent, with seven.

“When you have six guys in your lineup that have hit 20 home runs, and one of them’s a platoon player, you know that there’s a lot of power,” Girardi said. “We weren’t able to keep the ball in the ballpark, and it’s how this club is extremely dangerous.”