Koss will start at third base and bat ninth in Wednesday's game against the Giants.
Koss will pick up a second straight start at third base in place of Casey Schmitt (knee), who has been diagnosed with a torn meniscus that will likely require season-ending surgery. Though he currently sits atop the depth chart, Koss' run as an everyday player will be short-lived. Giants manager Tony Vitello said that Matt Chapman (abdomen) should be ready to come off the 10-day injured list at some point during the club's series with the Padres later this week, at which point Koss will shift back into a utility role.