Blackmon sustained the injury during his first at-bat of Tuesday's 6-2 victory over the Nationals, when he collided with pitcher Gio Gonzalez, who was covering first on a ground ball. Blackmon went 1-for-3 with a walk and two runs in that game, and 1-for-4 with a walk, an HBP and two runs in Wednesday's 12-10 victory over Washington.
Entering Friday, Blackmon had played in 100 straight games, all but three of them starts, after missing 13 games in April with turf toe in his left foot.
During the streak, Blackmon is hitting .481 with nine of his career-high 21 home runs, 15 RBIs, five doubles and a triple. He has also scored 20 runs and recorded a .525 on-base percentage.
The Rockies moved rookie David Dahl, originally slated to play left field, into the leadoff spot and into center field. Dahl, the Rockies' top pick in 2012 out of Oak Mountain High School in Birmingham, Ala., is considered a natural center fielder but has shown the ability to handle the corners.
The Rockies had planned to give Gerardo Parra his first career start and first appearance at first base. The Rockies have been using such players as Daniel Descalso, a middle infielder by trade, and Ryan Raburn, an outfielder, at first base as they cover for the absence of Mark Reynolds, who this week underwent surgery to remove a broken hamate bone from his left hand and is slated to miss four to eight weeks.
For Friday, Parra was moved to left field, and the left-handed-hitting Ben Paulsen received the start at first base.
Thomas Harding has covered the Rockies since 2000, and for MLB.com since 2002. Follow him on Twitter @harding_at_mlb, listen to podcasts and like his Facebook page. Ben Weinrib contributed.
This story was not subject to the approval of Major League Baseball or its clubs.