Extra bases

• Edwin Jackson threw a light bullpen session on Saturday, and the Cubs are continuing to monitor the right-hander's progress. Jackson has been on the disabled list since Aug. 21 with a right lat strain.

"We'll continue to monitor and see how he's doing," Renteria said. "We haven't set any hard dates. We'll see how he progresses and continue to make adjustments."

Jackson's last start was Aug. 20, and he is 6-14 with a 6.09 ERA in 26 starts this season.

• The Cubs have yet to sort out their soon-to-be six-man rotation. Felix Doubront, who picked up the win in his first start with the Cubs on Saturday, will be inserted into the mix for the final month. The Cubs have an off-day Thursday, and they have yet to announce who will start a three-game series against the Pirates, which opens on Friday at Wrigley Field.

• The Cubs will likely add one relief pitcher on Monday when rosters expand, then call up a few more players once Triple-A Iowa's season is over. Iowa didn't make the playoffs and will play its last regular-season game Monday against Oklahoma City.

• It isn't often that a visiting player catches a ceremonial first pitch, but Cubs hitting coach Bill Mueller did just that on Sunday. Mueller was behind the plate to catch a pitch from retiring DeSmet Jesuit High School coach Greg Vitello. Vitello was Mueller's coach, and is retiring after 35 years as the baseball coach.

• The Cubs will honor the Jackie Robinson West Little League team on Monday at Wrigley Field. The Chicago team won the U.S. title in the Little League World Series, and will meet some of the players prior to the game. They also will sing the seventh inning stretch from the field.

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.