Cardinals first baseman Lance Berkman found sleep difficult Saturday night. He said the resulting pain from a right knee injury sustained in that night's second inning was less distracting than the potential outcomes he weighed based on an MRI to be performed today.

Neither the club nor Berkman has yet to offer specifics about an injury that caused Berkman to crumple twice after receiving a chest-high throw from shortstop Rafael Furcal.

Manager Mike Matheny and assistant trainer Chris Conroy ran to Berkman and eventually had to help him from the field. Berkman voiced optimism Saturday that the injury wasn't a recurrence of the torn anterior cruciate ligament he suffered in November 2005. However, by Sunday he admitted the possibility is inescapable.

"If I've 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," said Berkman, 36. "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 it is."

Berkman advanced the possibility of having merely torn his meniscus Saturday night. Sunday he still exhibited acute stiffness around the knee. "I really can't do anything," he lamented.