EXCLUSIVE: One of the many mysteries surrounding the upcoming fourth season of This Is Us has been solved. The West Wing alum Tim Matheson will play Rebecca’s (Mandy Moore) father, Dave, in a key recurring role on NBC’s flagship drama series.

This Is Us has been teasing the Meet the Parents aspect of Season 4, including releasing a promo image from the season premiere of Rebecca (Moore) and Jack (Milo Ventimiglia) at the dinner where she introduces him to her parents for the first time.

THIS IS US — “Strangers” Episode 401 — Pictured: (l-r) — (Photo by: Ron Batzdorff/NBC) NBC

While we have seen Rebecca’s overbearing mother, played by Elizabeth Perkins, in previous seasons, the identity of her father had not been revealed until now. The producers are keeping mum on details about Dave’s character and storyline, but Moore has been dropping clues in interviews this summer, noting that “Rebecca is a bit of a daddy’s girl” and that “my father plays a bigger role in Rebecca and Jack’s relationship moving forward.”

Created by Dan Fogelman, the multi-generational, multi-time-frame family drama This Is Us stars Ventimiglia, Moore, Sterling K. Brown, Chrissy Metz, Justin Hartley, Chris Sullivan, Susan Kelechi Watson, Jon Huertas, Hannah Zeile, Niles Fitch, Logan Shroyer, Mackenzie Hancsicsak, Parker Bates, Faithe Herman, Eris Baker, Lyric Ross and Lonnie Chavis.

Fogelman and fellow co-showrunners Isaac Aptaker and Elizabeth Berger executive produce with John Requa, Glenn Ficarra, Ken Olin, Charlie Gogolak and Jess Rosenthal.

The series has nine Emmy nominations this season, for Brown, Ventimiglia, Moore, Sullivan, Angarano, Cephas Jones, Khosla, guest actress Phylicia Rashad, as well as nomination for Outstanding Drama Series.

Matheson is a series regular on the upcoming Netflix series Virgin River, and recently recurred on Showtime’s The Affair and CBS All Access’ The Good Fight. He’s repped by Gersh, LINK Entertainment and Jacobson, Russell, Saltz.

This Is Us returns for its fourth season Tuesday, September 24 at 9 PM on NBC.