Karros will start at third base and bat seventh in Monday's game in St. Louis.
After being called up from Triple-A Albuquerque on Friday, Karros started at third base in all three games of the Rockies' weekend series in Arizona, going 4-for-11 with two doubles, two walks, three RBI and two runs. The 23-year-old will stick in the starting nine Monday and should have a chance to settle in as the Rockies' everyday option at the hot corner for the rest of the season if he can remain reasonably productive at the plate.