WASHINGTON -- The Nationals could arguably have the best defensive infielders in the game in third baseman Ryan Zimmerman and first baseman Nick Johnson.

After Zimmerman was drafted in the first round of the 2005 First-Year Player Draft, general manager Jim Bowden compared Zimmerman's defense to Brooks Robinson, Scott Rolen and Mike Schmidt. Bowden has been proven right so far, as Zimmerman has shown a lot of range from his left to his right.

Johnson has similar range at first base. Last season, he was constantly diving for balls and preventing opponents from getting base hits.

But the big question is, how much offense can Johnson and Zimmerman provide? Injuries have prevented Johnson from reaching his full potential with the bat. He missed a month of the 2005 season because of a deep bone bruise in his right heel. It marked the sixth consecutive season in which Johnson had to go on the disabled list. He is a free agent after this season and he has to show Washington that he is worth an extension.

When healthy, Johnson is one of the most disciplined hitters in the game. Last season, he had a team-high .408 on-base percentage and drew 80 walks.

If Johnson finds himself on the disabled list again, look for Robert Fick to get the bulk of the playing time. Another favorite of manager Frank Robinson's, the left-handed-hitting Fick hit .265 with three home runs and 30 RBIs for the Padres in limited action last year. Marlon Anderson also can play first base, but he is expected to see most of his playing time at second base and in the outfield.

As for Zimmerman, the Nationals were hoping that he would reach the big leagues by 2007, but a lack of offensive production from third baseman Vinny Castilla and shortstop Cristian Guzman hastened the Nationals to promote the youngster last September.

Zimmerman became the second Nationals/Expos player in three years (right-hander Chad Cordero is the other) to reach the big leagues the year he was drafted. It helped that he hit a combined .336 with 11 home runs and 38 RBIs for Class A Savannah and Double-A Harrisburg.

The success in the Minor Leagues carried over into the big leagues, as Zimmerman hit .397 with six RBIs. Bowden then handed Zimmerman the third-base job last November after the GM traded Castilla to the Padres for right-hander Brian Lawrence.

But Zimmerman is taking nothing for granted. He still feels that he has to earn his way into the starting lineup.

Washington Nationals • Starters: Livan to lead retooled rotation • Bullpen: Cordero anchors Nats 'pen • Catchers: Nats search for backup • Corner IF: Defense is reliable • Middle IF: Questions abound • Outfielders: Guillen may not be ready • Bench: Bowden revamps with vets

"Now I can focus on just going into camp and playing my game this year," Zimmerman told MLBPLAYERS.com recently. "My only goal now is to make the team in Spring Training. I've heard all of the talk about the club trading Vinny Castilla and opening up third base for me, but I don't buy into any of that. I'm not taking any of that for granted.

"I believe I still have to win that job, so I'm going into camp with the idea that I have to earn my way onto the team and prove that I belong. If everything goes well with that, I just want to be consistent and productive."

Look for Jamey Carroll and Brendan Harris to battle to be Zimmerman's backup. Carroll is the most fundamentally sound player on the Nationals. However, a lack of run production may prevent Carroll from winning the role. He was given a chance to be the everyday second baseman after Jose Vidro went down with an ankle injury last May, but Carroll went into a slump. Carroll's struggles led to Bowden acquiring infielder Junior Spivey for right-hander Tomo Ohka, a trade Bowden now regrets because Spivey didn't play much due to a wrist injury, while Ohka became a quality starter for the Brewers.

Two things occurred this offseason that helped Harris become a strong candidate to become Zimmerman's backup. Harris played well for the Peoria Saguaros of the Arizona Fall League and also helped Team USA win the 2005 CONCEBE Regional Olympic Qualifying Tournament.

In the AFL, Harris was the Saguaros' best hitter, going 32-for-85 (.376) with one home run and 13 RBIs and he showed the Nationals that he could play shortstop, third base and second base.