With that in mind, MLB.com decided to handicap the list of candidates at those positions and see where they stand.
Nick Johnson vs. Dmitri Young
There is no more talk about Johnson's broken leg. He is playing great defense and running the bases like he did before the injury, which occurred on Sept. 23, 2006. A lot of people feel the Nationals will be better defensively if Johnson is in the starting lineup.
Young, on the other hand, can still hit and is the unquestioned leader of the team, but he is having problems losing weight because of diabetes and is considered a liability with the glove.
Ronnie Belliard vs. Felipe Lopez vs. Bret Boone
Belliard works his tail off and hits the ball hard every day. His bubbly attitude has made him a popular figure in the clubhouse.
Last year, Lopez had problems on and off the field. Now, by all accounts, Lopez's attitude is great, but it hasn't translated on the field. After Tuesday's action, Lopez was batting .205 (9-for-44).
Boone, who had been in retirement the last two years, is a long shot to make the team, but he is still determined to show he can be a starter. He is trying to get used to hitting breaking balls. Starting Wednesday, Boone will get at-bats in Minor League games.
Garrett Guzman vs. Willie Harris vs. Ryan Langerhans vs. Rob Mackowiak
Elijah Dukes was supposed to be the fourth outfielder, but he will now start in left field because of an injury to Wily Mo Pena.
A Rule 5 pick, Guzman is a pretty good outfielder, but just an OK hitter. Guzman showed some pop with the bat when he homered against the Orioles on Sunday.
Harris can play all infield and outfield positions. As a hitter, he can work the count. After Tuesday's action, he had a .415 on-base percentage.
Langerhans is an excellent outfielder with a great attitude, but the Nationals want more from him. Langerhans hasn't improved his hitting enough and he is second on the team with 10 strikeouts.
Mackowiak is just as versatile as Harris, but he hasn't played a Major League exhibition game because of an abdomen injury.
Bill Ladson is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.