VIERA, Fla. -- Right-hander Collin Balester will not be a member of the Nationals' rotation, as he was optioned to Triple-A Syracuse on Saturday morning.

The move means that right-handers Shairon Martis and Jordan Zimmermann will be the fourth and fifth starters in the rotation, respectively.

Zimmermann, the team's Minor League Pitcher of the Year in 2008, will start the season in the Minor Leagues and make his Major League debut on April 19 against the Marlins at Nationals Park. The Nationals don't need a fifth starter until then, because they have days off on April 9 and 14.

"I'm excited -- I kind of figured it would be that way," Zimmermann said. "Martis threw the ball well all Spring Training. We were pushing each other the whole time. He has the fourth spot, I have the fifth spot."

Zimmermann most likely will pitch for Syracuse, but the Nationals want to make sure that he pitches in a warm climate before April 19.

"I'm going to be honest with you: I wish we didn't have the days off that we have, so we can have him in the big leagues right away, because he has shown in this camp that he is one of our best pitchers, period, that we have," manager Manny Acta said. "He has shown he can give us a chance to win when he is on the mound."

For most of Spring Training, Zimmermann appeared to be the leading candidate to become the fourth starter, as he didn't up a run in his first four outings. But a bad case of the flu hurt him as he gave up five runs in two innings in his March 21 start.

Martis, on the other hand, had a 1.42 ERA with 11 strikeouts in five games. Acta said Martis was more aggressive in the strike zone this spring than he was during his September callup last year.

"I think Martis has received the least publicity and hoopla, but I think Martis has pitched better than anybody in camp," Acta said. "The numbers are there. He has a tremendous camp, laid low in the weeds, while everybody was talking about [other] guys. He just continued to pound the strike zone and put zeros on the board. He earned it."

Martis, who didn't know he made the team until the media told him at 9 a.m. ET, said he probably would have been in the Minor Leagues had he decided to play in the World Baseball Classic. Before he arrived in camp, Martis chose not to play for the Netherlands, because he felt had a 50-50 chance to be the Nationals' fifth starter.

"If I were in the Classic, I wouldn't have had as many starts with the Nationals and they wouldn't know what I have," Martis said. "I made the decision to stay here the whole Spring Training. I have more confidence in this league."

As for Balester, he was inconsistent on the mound, going 1-1 with a 6.75 ERA. Acta felt Balester was too caught up in the competition for the final two spots in the rotation and stopped being himself on the mound.

"We need Collin to go down there and get some consistency on his command and three pitches," Acta said. "He took the news very well. He is going to go down there and work hard. I'm sure we are going to be seeing him this year and for years to come."

Besides Martis and Zimmerman, the Nationals have John Lannan, Scott Olsen and Daniel Cabrera to fill out the rotation. Acta would rather take his lumps with a young staff than the veteran staff he had the last two years.

"What makes it more exciting is that most of the young guys come from our system. [We are not running] a tryout camp, like we did the last two years with six-year free agents," Acta said. "Whether the young guys do it or not, we are going to see, but I'm excited to have five guys that are 27 years old or younger. I can live with that. If these guys come together -- at least three of them are the real deal -- you have yourself a good rotation for a long time."