BALTIMORE — Luis Severino and Dellin Betances played catch on flat ground before the Yankees’ 9-4 win over the Orioles on Tuesday night at Camden Yards.

While Severino might be throwing off a bullpen mound Friday in Toronto, Betances didn’t know when he would take the next step in his comeback from upper arm troubles that have kept him on the IL all season.

“Flat [Wednesday]. I don’t know about a bullpen, I am not sure,’’ Betances said.

Like Betances, Severino hasn’t pitched this year because of shoulder problems.

With a nine-game lead over the second-place Rays in the AL East, Aaron Boone was asked about having home field advantage when the postseason starts.

Boone hesitated before answering.

“Of course we feel like we have a tremendous home-field advantage obviously playing at Yankee Stadium,’’ said Boone, whose club is 43-18 in The Bronx. “But we are such in the throes of grinding this now, that is a long way off. We are looking forward to today and rack up wins. I don’t think we will get too caught up in that right now. We are trying to win games.’’

Aroldis Chapman’s 30th save in 35 chances on Monday night gave the left-handed closer a seventh season of 30 or more saves. He is the 17th pitcher since 1969 to save 30 in seven seasons. Craig Kimbrel and Chapman are the only active pitchers to do it.

The Yankees won their 14th straight games at Camden Yards. It is the longest road winning streak at any single opponent in franchise history.

It also was the Bombers’ 11th straight victory against the Orioles, and their six homers upped their total to 38 this season at Camden Yards. That is the major league record for most home runs at a visiting ballpark.