The actor's brief 2010 romance with Knapp was kept quiet until it was reported she was expecting the star's baby, months after they split.

Phillippe stood by the model's bedside when she gave birth to little Kai in Los Angeles on 1 July (11), but according to the child's birth certificate, obtained by TMZ.com, the actor has not been legally named as a parent - the space was simply left blank.

However, the newborn's full name was listed as Kailani Merizalde Phillippe Knapp.

The Crash star, who recently split from actress Amanda Seyfried, has a daughter and a son with ex-wife Reese Witherspoon.