WILLIAMSPORT, Pa. -- Craig Kimbrel made his way around the Little League World Series complex on Sunday afternoon, signing autographs and meeting fans and kids during the Cubs' trip to Williamsport for the Little League Classic presented by GEICO. His next stop was on the mound, but it was a group of young players sitting in the stands behind home plate at Historic Bowman Field who stole the show.

Kimbrel was activated from the 10-day injured list prior to Sunday's 7-1 win over the Pirates, and was given the ninth inning to shake off some rust. As the closer shifted into his pre-pitch pose, a pack of Little Leaguers mimicked his motion by hunching over and raising their arms.

Kimbrel logged 15 pitches in two-thirds of an inning, during which he gave up a first-pitch, leadoff homer to Starling Marte and then hit Cole Tucker with a pitch. The closer then recorded a pair of strikeouts before manager Joe Maddon pulled the plug on his first big league outing since Aug. 3.

Chicago optioned righty Duane Underwood Jr. to Triple-A Iowa to clear a spot on the active roster for Kimbrel, who had been sidelined with right knee inflammation. The Cubs also promoted outfielder Mark Zagunis from the same affiliate to serve as the 26th man for the Little League Classic game against the Pirates.

Kimbrel had been on the IL since Aug. 4, but he had thrown two bullpen sessions in the past five days without any issues.

In 15 appearances this season, the 31-year-old Kimbrel has notched nine saves with a 6.08 ERA. He has 19 strikeouts against eight walks in 13 1/3 innings, which signed him to a three-year contract worth $43 million in June.

The Cubs also received good news on Saturday about setup man Steve Cishek, who threw a bullpen session with no problems at PNC Park. Cishek (on the 10-day IL with a left hip issue) is eligible for activation on Tuesday and appears to be on pace to return on time.

Cishek hoped the time off would put both him and Kimbrel in position for a strong finish to this season.

"It can't hurt, that's for sure," Cishek said. "It's definitely going to help, just how we feel going into this. Obviously, nothing's guaranteed, but I feel like this last 10 days gives you the best opportunity to have your best feel out there for the run. So, like I said, it can't hurt."