Estrada (knee) has been throwing at the Padres' spring-training complex in Arizona, per MLB.com.
When Estrada landed on the IL with right knee inflammation June 5, it was initially believed that he wouldn't be out long. However, the righty reliever has now been sidelined nearly a month, and the Padres haven't shared a timeline for when he will return. San Diego recently lost setup man Jason Adam to the injured list because of a shoulder strain, so Estrada's continued absence has taken on extra significance.