Marmol was injured in the seventh inning of Friday night's 13-inning marathon when he delivered a pitch to the Brewers' Corey Hart. Entering the game with a three-run lead, Marmol already had given up a run on an Aramis Ramirez double.
"Marmol's going on the DL and Casey Coleman will be here sometime during the game," Cubs manager Dale Sveum said.
Coleman was en route to Milwaukee from Fresno, Calif., where the Iowa Cubs had just wrapped up a series. His flight was not expected to land in Milwaukee until 1:20 p.m. CST Saturday, nearly 1½ hours after the first pitch.
There is a good chance Coleman could be pressed into action not long after he arrives. The Cubs used every member of the bullpen Friday night, and Kerry Wood and Rafael Dolis (two innings each) were considered off-limits by Sveum.
Six of Coleman's seven appearances at Iowa were starts. He posted a 2-3 record with a 3.48 ERA in 33 2/3 innings and had 30 strikeouts and 16 walks. He is expected to be used as a long man out of the bullpen.
"He's a kind of guy you can use in different roles depending on what's going on that day," Sveum said. "He has the slider, he has different arm angles. He's a guy you can use if right-handers are coming up. But he's definitely a guy you will want to use two innings whenever you use him."
Marmol was expected to undergo an MRI Saturday in Chicago.
"We'll find out how bad it is but he got really sore when he was walking out last night," Sveum said. "It seemed to actually get worse. We'll just have to see."
Sveum added that it would be an option to send Marmol to Iowa for a rehab stint before he returns to the active roster. Marmol has struggled all season, posting a 6.35 ERA in 15 appearances, with a loss and two blown saves.