The new parents "are elated with her arrival," we hear. "Alina feels good," and it was a "smooth delivery," says the source.

The actor was celebrating his win for "The Brutalist" at an intimate bash that turned into a dance party thrown by CAA at the Chateau Marmont.

Outside the restaurant, another source tells us the pair were so enveloped in their own world, they had no idea they were being followed by paparazzi.