Strop will land on the injured list with a yet-to-be-specified ailment while the Cubs also recall reliever Duane Underwood from Triple-A Iowa, as Jesse Rogers of ESPN first reported.
Strop has a 5.20 ERA in 32 appearances and has really struggled recently. While he wasn't charged with any runs in a 3-2 loss to the Brewers on Friday, he hit the first batter he faced in a key moment and then promptly allowed the go-ahead two-run single. In a 5-4 loss to the Giants on July 22, Strop took the loss in allowing three earned runs late.
Underwood, 25, has a 5.23 ERA and 1.53 WHIP in 28 appearances at Triple-A this season.