PITTSBURGH -- An unexpected break didn't stop the steady stream of pitchers to the injured list for the Pittsburgh Pirates.

The team placed opening day starter Joe Musgrove on the 10-day IL Tuesday with what manager Derek Shelton called a right triceps issue. The Pirates scratched Musgrove (0-3, 6.75 ERA) before Sunday's start against Detroit with what Shelton called an ankle injury.

Musgrove is the sixth Pittsburgh pitcher to be placed on the injured list this season. The list includes starter Mitch Keller and relievers Nick Burdi, Clay Holmes, Michael Feliz and Kyle Crick. It doesn't include closer Keone Kela, who has yet to pitch this season after testing positive for COVID-19. The Pirates began the truncated season with starters Jameson Taillon and Chris Archer already out due to injury.

Travis Williams will start when Pittsburgh travels to Cincinnati for a four-game series beginning on Thursday. The Pirates were supposed to be in St. Louis on Tuesday, but their three-game set with the Cardinals was scratched while St. Louis continues to grapple with a COVID-19 outbreak.

The injuries have forced Pittsburgh to get aggressive in finding arms healthy enough to help a team that currently has the worst record in the majors (3-13). The Pirates signed veteran Henderson Alvarez on Sunday. Alvarez last pitched in the majors with Philadelphia in 2017. On Tuesday, Pittsburgh claimed right-hander Nick Tropeano off waivers from the New York Yankees. Tropeano is 12-15 with a 4.51 ERA in 42 career appearances (39 starts) with Houston and the Los Angeles Angels.

"Obviously we didn't know coming in to this year what it was going to be like," Shelton said. "No one is going to feel sorry for you, so we just have to continue to execute, to get better, to continue to teach and get guys out there."