Fowler, 24, a rookie, has been the Rockies' primary center fielder for much of the season. He was hitting .270 with four home runs, 33 RBIs and 26 stolen bases -- most of any National League rookie -- in 113 games before knocking a foul ball off his knee on Aug. 24.
Surging Carlos Gonzalez (.296, 11 HRs, 24 RBIs in 69 games) started in center Wednesday. Manager Jim Tracy went with the same lineup he used in Tuesday's 3-1 victory. Recent callup Eric Young Jr. started at second base, on the heels of a double and a home run, and Gonzalez batted second.
In other injury news, Tracy said shortstop Troy Tulowitzki and third baseman Ian Stewart, both of whom missed Wednesday's game with back stiffness, "are feeling much, much better." Tracy didn't rule out starting either or both in the finale of the four-game set with the Reds on Thursday afternoon.
Closer Huston Street, out with a sore right biceps tendon, reported feeling better Wednesday. Left-hander Franklin Morales has stepped in as closer and gone 5-for-5 on save chances in Street's absence.
Righty Aaron Cook, who hasn't appeared in a game since leaving his Aug. 21 start with shoulder soreness, threw from the slope of the mound. A bullpen session could occur next week, as Cook (10-6, 4.47 ERA in 25 starts) hopes to return before the end of the regular season.
Right-hander Ubaldo Jimenez (13-10, 3.32 ERA), who has emerged as the staff's most-feared pitcher this season, rescheduled his bullpen session from Wednesday to Thursday because of the left hamstring strain he suffered while running the bases during his last start.
Jimenez is scheduled to start Sunday on the road against the Padres, but the Rockies want to make sure the hamstring doesn't affect his throwing motion before committing to giving him that start.
Thomas Harding is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.