(Alex Brandon /AP)

Though the Nationals’ scheduled starter for Sunday night’s remains undecided, Ross Ohlendorf will “probably” start against the Mets, Manager Davey Johnson said.

Johnson had also considered Tanner Roark, who has excelled in relief, and ace Stephen Strasburg, who pitched only two innings last night because of a rain delay. But he may need to use Roark out of the bullpen tonight, and he wants to keep Strasburg on his usual routine.

If Johnson does not use Roark out of the bullpen tonight, “then I might flip-flop,” Johnson said. “But I did tell Roark he might be the first man up today.”

Ohlendorf started Tuesday night and allowed one run over five-plus innings. The Nationals are 4-0 in Ohlendorf’s starts this year, but Johnson worries about Ohlendorf’s stamina. In his last start, he allowed a solo homer to the first batter he faced in the sixth inning as he threw four fastballs that hummed at no faster than 85 miles per hour.

Roark relieved Ohlendorf and continued his eye-opening first month in the majors. Roark has a 1.04 ERA over seven appearances He started 11 games at Class AAA Syracuse this season and has been a starter for most of his minor league career.

Johnson seems to be deciding between Roark and Ohlendorf, but he has yet to rule out Strasburg. Last night, Strasburg allowed no runs over two hitless innings before a 78-minute rain delay knocked him out. He threw only 22 pitches, but Johnson thought Strasburg may be best served to go through his usual routine between starts.

“It’s a little change in what he’s used to doing,” Johnson said. “It’s not something that has to be decided right now. We’ll see how he feels. And that can always change on Sunday.”

Wednesday night, Strasburg himself said he would prefer to pitch on usual four-day rest, a nod to the rest of the Nationals’ rotation.

“I don’t really think it would matter,” Strasburg said. “Everybody healthy is pitching well. So I’d say keep it going.”

If Strasburg has any doubts about coming back, Johnson would probably wise to let the rotation roll on as usual. At 25, Strasburg has not been the kind of pitcher who responds to variables well.

“He still hasn’t been in the major leagues that long,” Johnson said. “He’s perfectionist.”

Strasburg felt tightness in his back during the delay, but the Nationals and Strasburg considered it to be standard stiffness and nothing to worry about. Still, Johnson believes it could affect Strasburg if he comes back on short rest.

“I’m not really concerned about it,” Johnson said. “But I’m sure he would be. He wants to be 100 percent and put his best foot forward. We’ll see how he is today, throwing and playing catch.”