The Arizona Diamondbacks bolstered their pitching staff on Monday with the return of Michael Soroka from the injured list and the signing of Zack Littell to a one-year contract.

To accommodate the additions, the team designated veteran right-hander Paul Sewald for assignment and optioned Kade Strowd to Triple-A Reno. Soroka returns after missing nearly two months due to left hip discomfort, boasting an 8-3 record and 3.07 ERA prior to his injury. He is scheduled to start Monday's game against the Colorado Rockies.

Littell, who posted a 7-8 record and 4.97 ERA with the Washington Nationals over 23 appearances this season before being released, is expected to join Arizona's bullpen. Meanwhile, Sewald, 36, had served as the D-backs' primary closer but struggled recently, allowing 11 earned runs over his last seven outings while blowing two saves. His season totals include a 6.23 ERA and 24 saves.