Sean Marshall had to leave his start for Triple-A Iowa on Thursday after 3 2/3 innings because of a pulled hamstring. He had given up five runs on six hits in the 8-3 loss to Omaha.
"He'll miss at least one start, and we'll see," Cubs manager Lou Piniella said of Marshall, who made 13 relief appearances for the big league team before he was sent to Iowa. "I know we've been talking a little bit about another left-hander, and we'll have to wait."
Marshall, who was 7-8 with a 3.92 ERA in 21 games, including 19 starts, last season, was to be examined Friday in Des Moines, Iowa.
Meanwhile, lefty Rich Hill, who is on Iowa's disabled list with back spasms, was able to throw 50 pitches on the side Thursday. The left-hander, who opened the year in the Cubs' rotation, will throw a simulated game on Sunday.
"We'll see where he's at," Piniella said of Hill, who was 1-0 with a 4.12 ERA in five starts before he was optioned to Iowa.
Right now, the Cubs have one left-hander in the rotation in Ted Lilly, and one in the pen in Scott Eyre. Piniella would like another southpaw starter.
"Through the Los Angeles series [next week], we're fine with right-handers," Piniella said. "Nine of our 11 pitchers are all right-handed. To get the best out of our bullpen, having another left-hander in the bullpen wouldn't hurt. We had that coming out of Spring Training but it didn't stay that way."
Hill will need more than one simulated game before he can be recalled.
"We'll see where he's at physically, and where he's at command-wise," Piniella said. "I think that will be determined as to when he starts over there. Not for here, not right now."
Rookie Sean Gallagher, who took the loss in his last start against the Houston Astros on Wednesday, will stay in the rotation and make his next start Tuesday against the Dodgers.
Carrie Muskat is a reporter for MLB.com This story was not subject to the approval of Major League Baseball or its clubs.