If CC Sabathia and Luis Severino weren’t on the injured list, there would be no need for the Yankees to contemplate using a reliever to start Monday night’s game against the Tigers at Yankee Stadium.

However, that’s not the case.

Suspended for the first five games of the season, Sabathia will slide to the IL on Wednesday where he will continue the road back from knee surgery and having a stent inserted into a blocked heart artery this past offseason. Severino is with Sabathia in Tampa because of inflammation in his right rotator cuff.

So, after Masahiro Tanaka, James Paxton and J.A. Happ started the first three games, manager Aaron Boone said Domingo German will pitch at some point in Monday night’s game.

Boone wasn’t clear when the right-hander would surface and there is a chance the manager will tab a reliever to handle the first and/or second innings before calling for German.

“It will depend on usage. German will pitch one way shape or form,’’ Boone said.

Working on four days’ rest, Masahiro Tanaka will start against the Tigers on Tuesday. Beginning Wednesday, Sabathia’s suspension ends and the Yankees return to having a full 25-man roster. The plan at the end of spring training was for right-hander Jonathan Loaisiga to be recalled from the minor leagues and make that start but that can change.

Sabathia is slated to pitch in a minor league game Monday.

Yankees went 6-for-29 (.207) in the three games with runners in scoring position and stranded 14 runners on Sunday and 33 in the series. The 14 stranded runners were the most since the Yankees left 16 on base on April 30, 2017, also against the Orioles.

DJ LeMahieu reached base in all five plate appearances Sunday. He walked in the third and fourth innings, singled in the sixth, was hit by a pitch in the eighth and had an RBI single in the ninth.

According to Boone, Dellin Betances threw a bullpen session in Tampa on Saturday and is progressing as he rehabs a right shoulder impingement.

“Another good day for Dellin. I feel like he’s moving in the right direction. He’ll long toss again, throw another side and then face hitters,’’ Boone said. “I feel good about how he’s feeling and responding each day.’’

Luke Voit was the Yankees’ DH on Opening Day when Greg Bird played first base. In the second game of the season Saturday, Voit was at first, Bird on the bench and Miguel Andujar was the DH. Sunday, Bird was back at first and Voit in the DH spot after making a throwing error in the second on Saturday and failing to scoop a LeMahieu throw in the ninth that helped the Orioles score twice in a 5-3 win.

Starting Bird at first over Voit twice in the first three games could be seen as the Yankees believing Bird is the better defender, but Boone doesn’t necessarily view it that way.

“Early in the season things happen,” the manager said. “ Guys make mistakes. He makes a really good play [robbing Rio Ruiz of a hit] and gets a little carried away trying to make an amazing play with the throw to second. You have a conversation saying, ‘Rein it in. Stay within yourself.’ Anytime you have scoop plays, those are difficult plays. I feel like he made a lot of progress from where he was [last year].’’

Voit went 1-for-5 Sunday while Bird went 0-for-3 and walked twice.