(Alex Brandon /AP)

The Nationals have still come to a decision in the fifth starter competition between Tanner Roark and Taylor Jordan, but they at least know when they will unveil their choice.

Both Roark and Jordan will pitch in Saturday’s exhibition against the Tigers at Nationals Park, Williams said, with Roark likely to start. Williams plans to announce the  fifth starter – who will start the home opener April 4 – following the game.

Williams insists the choice remains fluid. “There’s been no decision made,” Williams said. The Nationals want both right-handers to throw Saturday in order to stay on pace to start their seasons, either in the majors or minors. They will pitch on the same day, and the Nationals will take the choice to the wire.

“There’s no rhyme or reason to either thought in that regard,” Williams said. “They both need to pitch. We certainly want to, regardless of decision, see them both pitch. It’s good prep for both of them heading into the season.”

Williams reiterated that the loser in the position battle between Roark or Jordan will be sent to Class AAA, not used in relief. After the Nationals released Chris Young yesterday, they need a viable sixth starter to stay fresh in the minors. Williams named Aaron Barrett their final reliever yesterday.

“Both of these guys have been groomed to start this year,” Williams said. “That’s important for us. It’s important for us to have somebody, if something happens, that they’re ready. They’re deserving of the every fifth day.”

The Nationals batted the idea of Roark-or-Jordan around in meeting rooms all spring. “Could you go wrong if it’s one over the other?” Williams said. “I don’t know if you could.” General Manager Mike Rizzo, assistant general manager Bryan Minniti and the coaching staff have all given their input.

“I invite that. I like that, especially being the new guy, not knowing everybody yet,” Williams said. “Although we’ve been here six weeks, it’s not like I’ve know them for years and years. It’s important to me.”

Doug Fister, now building arm strength after his recovery from elbow inflammation, remains on track throw 65 pitches in a minor league game Thursday. If all goes well, Fister will make one more start – either in a simulated game or in extended spring training – before making his regular season debut for the Nationals April 6 against the Braves.

The Post Sports Live crew helps Matt Williams fill out the Nationals starting rotation by offering suggestions of who to name as the fifth starter. (Post Sports Live/The Washington Post)