Lance Berkman was diagnosed with a torn meniscus in his right knee on Monday and will seek a second opinion before the team sets a timetable for his return.
The Cardinals aren't ruling out ACL damage because tests were "uncertain." If Berkman suffered no ACL damage, he could return in six weeks, general manager John Mozeliak said.
When Berkman left Saturday's game, Dodgers' physicians on site at Dodgers Stadium on Saturday told the St. Louis Post-Dispatch Berkman probably had a torn ACL. Berkman had ACL reconstruction surgery in 2005.
Berkman was placed on the disabled list Sunday but for now the tone in the Cardinals' clubhouse is one of cautious optimism.
"If I've re-torn my ACL or something like that, I'd certainly get it fixed but you don't know how psychologically you're going to come back from something like that," Berkman told The Sports Xchange. "I'm not talking from the standpoint of being scared of hurting it again. I'm talking about doing everything it takes to come back and play again at an elite level. I think that's a legitimate question I'm going to have to answer if, in fact, it turns out to be something more serious than we hope that it is."
Berkman was replaced on the roster by Matt Adams, a top prospect who had two hits in Sunday's game.
The Cardinals have other options at first base, including Allen Craig and Matt Carpenter. Craig, however, is also on the disabled list after a strong start to the season and durability has become a concern for the right-handed slugger. Carpenter started Monday's game at third base to give David Freese a day off.