The Cardinals announced Sunday that Pete Kozma will start the season on their 25-man roster after being forced to place second baseman Mark Ellis on the 15-day disabled list.
Ellis, who signed with the Cardinals in the offseason as a free agent, dealt with right patella tendinitis during spring training and said he re-aggravated his knee when he slipped on a soggy field during a March 25 game.
Ellis played in a spring training game the next day, but has been limited since.
Ellis was on the field when the team worked out at Great American Ballpark in Cincinnati on Sunday. But he did not take ground balls with the other infielders.
"I'm disappointed," said Ellis, who spent two seasons with the Los Angeles Dodgers before signing with St. Louis. "I felt like this was the best thing for the long haul of the season. If you have to miss time, miss it now and be ready for the rest of the season."
The team can backdate Ellis' disabled list stint to March 27, making him eligible to return April 11.
In the meantime, Kozma, who was the team's primary shortstop much of 2013, will remain on the roster as a utility infielder.
"It's just something that's got to heal and get better for me to be as effective on the field as I can be to help the team win games," Ellis said. "It's one thing to go out there and play hurt, but to help the team win ballgames, it needs to get a little bit better."