Castro will start at third base for Tuesday's Grapefruit League game against the Cardinals, Mark Zuckerman of MASN Sports reports.

EDGE Analysis

The Nationals have stood by Carter Kieboom as their Opening Day third baseman all spring despite his struggles at the plate, but all of a sudden, the youngster's starting job doesn't seem so secure. One game at the hot corner for Castro doesn't necessarily mean that he's more than a contingency plan at third, but if the team does decide Kieboom is better off regaining his confidence at the alternate training site (and eventually Triple-A) to begin the season, Castro could move to third base on a more permanent basis, making room for Luis Garcia at second base. Either way, the 30-year-old infielder is locked into a starting spot, and Castro has enjoyed a strong spring with a .333/.375/.567 slash line over 32 plate appearances.