Sylvester Stallone to Guest Star on 'This is Us'

Frazer Harrison/Getty Images for LACMA

Actor Sylvester Stallone attends the 2016 LACMA Art + Film Gala honoring Robert Irwin and Kathryn Bigelow presented by Gucci at LACMA on October 29, 2016 in Los Angeles, California.

Rocky and The Expendables icon Sylvester Stallone has booked a guest appearance on NBC's family drama, This is Us.

"Can you guess what special guest star we're going to see in Season 2? The one and only... @TheSlyStallone! #ThisIsUs," the show's Twitter account said Thursday.

Starring Milo Ventimiglia, Mandy Moore, Sterling K. Brown, Chrissy Metz and Justin Hartley, the flashback-heavy series follows the lives of a pair of white twins and the same-aged, black brother their parents brought into the family the day they were born. Season 2 is to begin Sept. 26.

NBC Announces Fall 2017 Premiere Dates

NBC Announces Fall 2017 Premiere Dates

When to start watching the returns of 'This Is Us' and 'Will & Grace', the debuts of 'The Brave' and 'Law & Order True Crime' and more!

By Karen Butler

Originally published in UPI Entertainment News.