Mandy Moore is celebrating Milo Ventimiglia's 41st birthday.

The 34-year-old actress dedicated a sweet post to Ventimiglia on Instagram on the actor's 41st birthday Sunday.

Moore shared a playful photo of herself and Ventimiglia wearing mustaches on the This is Us set. The pair co-star as Rebecca and Jack Pearson on the popular NBC series.

"As remarkable as Jack Pearson is, this guy is even better," Moore captioned the post. "Happy Birthday, @miloanthonyventimiglia. Our job is so much fun because we get to do it together. Can't wait to get back to it. [Love] you, Mi!! #thisisus."

Ventimiglia thanked Moore and other well-wishers Sunday on Twitter.

"Grateful to be here (thanks Mom + Pop). Thanks for the birthday wishes all. Love each other, love always. MV," he wrote.

This is Us co-stars Sterling K. Brown, Chrissy Metz and Justin Hartley as Jack and Rebecca's three children. NBC announced in June that the show will return for a third season in September.

"There's no party like a Pearson party. #ThisIsUs. Season 3. September 25," the series confirmed on its official Twitter account.