VIERA, Fla. -- When they start the regular season against the Marlins on April 6, the Nationals will carry four starting pitchers and seven relievers. Washington doesn't need a fifth starter until April 19 because of the off-days it has on April 9 and April 14.

That means, according to manager Manny Acta, the Nationals will carry an extra position player on the 25-man roster.

Acta declined to say which extra player will go with the team. It's doubtful that Washington will carry three catchers. Only one person will back up starter Jesus Flores. The extra player will be an infielder or an outfielder.

Kory Casto, who is out of options, could be that extra player. He can play the corner outfield and infield positions.

If the Nationals need power off the bench, Wily Mo Pena could be the guy. However, he is coming off his worst season because of a shoulder injury.

The Nationals need left-handed hitters off the bench and Dmitri Young, who is currently off the 40-man roster, could be a fit there.

In other news, right-hander Terrell Young will have an MRI on his right shoulder on Wednesday. Young, who is a Rule 5 Draft pick, has given up five runs in his past 4 2/3 innings.

Right-hander Julian Tavarez flew to the Dominican Republic on Wednesday to pick up his work visa. He hopes to participate in an exhibition game sometime this week.

Flores, who hasn't played in an exhibition game since Feb. 28 because of a sore right elbow, will play against the Astros on Saturday.