Molina served as the designated hitter in the series opener on Friday. However, the imPACT concussion screening that he receives daily showed regression in his condition on Saturday, so Molina was held out of the lineup entirely on Saturday. He still has not been cleared to catch, but the club considered first base a suitable assignment.
"It's not catching, but it's more than DH'ing," manager Tony La Russa said. "We'll see how he comes out of it."
With left-hander Jon Lester on the mound for Boston, La Russa chose not to play lefty-swinging Chris Duncan at first base. The Cardinals are without superstar first baseman Albert Pujols, who is on the disabled list due to a left calf strain.
Matthew Leach is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.