CHICAGO -- The Chicago Cubs have a razor-thin margin for error as they attempt to hold onto first place in the National League Central down the stretch.
So if there was a time when a team that has already experienced its share of injuries this season couldn't afford another setback to its roster, it's now.
Already in a difficult stretch when fatigue has become an issue heading into Saturday's game against the Cincinnati Reds, the Cubs will have to play the remainder of the regular season without one of their most valuable bullpen arms.
Before Chicago won its third game in its last four with a 3-2 victory over the Reds on Friday, the team announced closer Pedro Strop will be sidelined with a moderate hamstring strain.
"He's been so big for us now," Cubs manager Joe Maddon told reporters Friday, according to team's official website. "To be without him for the next couple of weeks will be difficult."
As Brandon Morrow -- who started the season as the Cubs' closer before sustaining a bone bruise on his right arm -- moves closer after not pitching since July 18, the Cubs will have to put a new reliever into the closer's role.
Maddon is confident he has plenty of candidates, but that replacing Strop's confident contributions will be a challenge.
Jorge De La Rosa picked up the save in Friday's victory when he stranded the tying runner in scoring position to preserve the Cubs' one-run win over the Cincinnati Reds. Now, Maddon will look for others to follow De La Rosa's lead.
"It's going to be (about) who gets the last three outs based on what happens before that," Maddon said. "And we'll see how it all shakes out."
After being shut down by Matt Harvey early only to get to the Reds for three seventh-inning runs to capture the series opener, the Cubs will attempt to keep rolling behind Jon Lester, who will start in Saturday's matinee.
Lester (15-6, 3.57 ERA) had rediscovered his winning ways before he took a loss in his last start against the Milwaukee Brewers when he allowed three runs and struck out seven in 5 2/3 innings. Lester is 6-1 with a 4.18 ERA in 15 career starts against the Reds.
The Cubs aren't the only ones dealing with injuries to their pitching staff. On Friday, the Reds announced that right-hander Lucas Sims will miss the remainder of the season due to a muscle strain near his shoulder.
Sims sustained the injury last weekend when he pitched 1 2/3 innings in relief against the San Diego Padres and allowed four earned runs and three hits before saying he felt some shoulder discomfort.
Sims was a September call-up and had joined Cincinnati's starting rotation. But interim manager Jim Riggleman told reporters Friday that the injury will prevent Sims from pitching.
"These things seem to take a while," Riggleman said, according to the Reds' official website. "I don't know how serious it was."
Cody Reed will take the mound for the Reds on Saturday. Reed (0-2, 5.08) will make just his fifth start of the year. He started the season in bullpen but was part of a shift when the Reds changed their rotation in August.
Reed is coming off a no-decision against the Los Angeles Dodgers when he allowed three runs and struck out five in four innings. Reed is 0-3 with a 12.79 ERA in five career outings (three starts) against the Cubs.