“It's nice to know that the material attracts the greats even like Sly. And to know that he'd want to be a part and play with us, it's a very good feeling, so we're thrilled," Ventimiglia told ET
following the announcement. "I'm personally excited, too, because his character's involvement gives Jack a lot. Because you imagine if Sylvester Stallone is Kevin's movie idol, where'd he learn that from? Probably from Jack, probably from dad."
Stallone joins a rich stable of past guest stars on the Emmy-nominated series, including Howard, Katie Couric, Katey Sagal, Brad Garrett, Seth Meyers, Jimmi Simpson and Elizabeth Perkins.