Chicago Cubs pitcher Pedro Strop will not pitch again during the regular season after suffering a moderate hamstring strain in Thursday's win over the Washington Nationals. 

Strop, who was injured while running to first base in the Cubs’ win over the Washington Nationals Thursday, underwent an MRI on Friday that confirmed the diagnosis. 

The Cubs say that it is unknown whether Strop would be able to pitch in the playoffs, and that they will continue to monitor his progress. 

Strop has been filling in for Brandon Morrow as the team’s closer, and has a 2.26 ERA and 13 saves this season. In his absence, the Cubs will likely turn to Jesse Chavez and Justin Wilson, adopting more of a closer-by-committee approach to the back end of their bullpen.