Marmol started the seventh inning Friday night against the Brewers and retired the first two batters he faced before walking Ryan Braun. Aramis Ramirez then hit an RBI double off the right-field wall to cut the Cubs' lead to 4-2.
Marmol was ahead in the count 1-2 to Corey Hart when catcher Welington Castillo went to the mound and signaled to the dugout. Marmol told Castillo he was OK, but assistant athletic trainer Ed Halbur and manager Dale Sveum went to the mound. After a few throws, Marmol was pulled.
"You could tell he wasn't right," Sveum said.
Marmol was wearing a large wrap on his right leg after Friday's 8-7, 13-inning loss to the Brewers.
"It hurts," he said.
If the Cubs had to call up a pitcher, it would most likely be Scott Maine, who would give the team another left-hander in the bullpen.
Carrie Muskat is a reporter for MLB.com. She writes a blog, Muskat Ramblings, and you can follow her on Twitter@CarrieMuskat. This story was not subject to the approval of Major League Baseball or its clubs.