CHICAGO (AP) — Chicago Cubs reliever Pedro Strop needs arthroscopic surgery on his left knee and will be sidelined four to six weeks. The Cubs announced Thursday that an MRI revealed a meniscus tear. Strop was injured fielding a grounder in the eighth inning of Wednesday’s victory over the Los Angeles Angels. He was placed on the 15-day disabled list.

The timetable would make it possible for Strop to return before the end of the regular season and be available for the postseason. The NL Central-leading Cubs had planned to use Strop and Hector Rondon as setup men for closer Aroldis Chapman, who was acquired last month. The 31-year-old Strop has a 2.89 ERA in 50 games with Chicago this season.

The Cubs recalled right-hander Justin Grimm from Triple-A Iowa.