Ross Detwiler. (Photo by John McDonnell/The Washington Post)

Manager Matt Williams was in a tough spot on Thursday. Jordan Zimmermann was scheduled to start in the series finale against the New York Mets but was so ill with the flu that he was scratched in the morning and sent home to Washington ahead of the team to rest. Tanner Roark’s start was moved up a day, and he delivered a strong six innings on short notice. The Nationals hope that Zimmermann will be ready to start Friday’s home opener against the Atlanta Braves, but aren’t sure. If the right-hander isn’t feeling better, the team will have to scramble to fill innings with a combination of relievers.

Ross Detwiler, the former left-handed starter moved to the bullpen in spring, was the logical choice to start on Friday. But he hadn’t pitched since March 26 and, as a result, was scheduled to pitch on Thursday because he needed to throw. And Williams stuck with that plan, using Detwiler Thursday for two innings.

“We don’t know how [Zimmermann is] gonna feel when he gets to the ballpark in the morning,” Williams said after Thursday’s 8-2 win. “But we needed to get [Detwiler] in a game. We didn’t want to wait too long before he pitches. And it was the perfect opportunity to get him out there [Thursday] and he did well.”

Williams said the Nationals’ training staff will monitor Zimmermann on Thursday night and evaluate him on Friday morning. Zimmermann’s symptoms arose overnight. He was up all night with stomach pain, vomited and developed a fever. Williams refused to put odds on Zimmermann’s chances of starting . (“I couldn’t tell you. We don’t want to send him out there with him being really sick.”) But Zimmermann feeling well enough to start would alleviate one of Williams’s headaches. Stephen Strasburg is starting on Saturday and Taylor Jordan won’t be available until Sunday after a Tuesday simulated game.

“I saw Jordan getting whatever he need to get [from the trainers] and he’s going to be fine [Friday],” Detwiler said. “He wanted to go [Thursday]. They held him back. I have no doubt.”

If not, the Nationals could turn to a combination of bullpen arms such as long reliever Craig Stammen and Jerry Blevins, each capable of throwing multiple innings, along with Aaron Barrett, Tyler Clippard, Drew Storen and Rafael Soriano. After Thursday’s game, Stammen said he hadn’t been told if he was starting. Detwiler said he could pitch an inning on Friday.

Detwiler came on in the seventh inning to relieve Roark and walked the first batter he faced. He admitted it was an unusual feeling coming out the bullpen again in a major league game but once he started pitching it felt the same again. He last pitched in relief in 2012. He escaped the seventh inning with a strikeout and two flyouts. He notched two flyouts and a lineout in the eighth inning, hitting 94 mph on his fastball and mixing in the occasional curveball.

“It’s a little weird [coming out of the bullpen],” he said. “That really doesn’t bother me. I’ve been able to stay in shape and throwing every day. It’s just a matter of getting a feel for the offspeed especially. It’s a little different because you’ve got to have it right out of the gate instead of getting a feel for it in a couple innings.”

“At one point, you’re happy to go in the bullpen, because you want to be in the big leagues,” pitching coach Steve McCatty added. “The next time, you feel like you’re a starter and you have to go in the bullpen. It’s not as easy a transformation, transition. But he’s doing fine with it. I thought he threw the ball well.”

Thursday was also a good opportunity for Detwiler to pitch because he could enter the game in relief of a right-handed starter and face the bulk of the Mets’ left-handers. Of the seven batters he saw, Detwiler faced three left-handers. In the past as a starter, coaches pushed Detwiler to use more offspeed pitches. In the bullpen, he doesn’t have to rely as much on his secondary pitches.

“Now it gives him a chance to rare back and throw it,” McCatty said. “You still got to pitch out of there. But I still think he’s going to be a big part of that mix down there.”