Mauricio Dubon only has been in the majors for a few days, but he's already showing why the Giants acquired him at the deadline and why he figures to be part of the team's long-term future. And the rookie infielder never will forget Monday, a day of career firsts for the young Giant at Busch Stadium. First, Dubon notched his first career double, lacing an offering from St. Louis Cardinals ace Adam Wainwright off the left-field wall.