The 24-year-old 'High School Musical' heartthrob gets down and dirty with the 44-year-old married mother-of-four in the new sexual thriller, and admits it was a dream come true because he has always had a crush on her.
He told television show 'Daybreak': ''Nicole is so gorgeous.
''It was everything you dreamed of. She was such a lovely person. I pinched myself every day, especially after doing love scenes with Nicole Kidman.
''It was the highlight of my life.''
And it isn't just the 'Rabbit Hole' star's looks he admires. Speaking about their time on set, he continued: ''Nicole was something else and was always in character. She didn't get weird method, like some actors do, but I have never seen anyone so centred.''
But with Nicole already spoken for, Zac - who previously dated Vanessa Hudgens and was recently linked to 'Mirror Mirror' star Lily Collins - has a good idea about the kind of woman he would like to settle down with one day.
He said: ''[My wife will have] a sense of ambition and a sense of freedom, which is a careful mix. You have to balance those two. I haven't exactly found it yet.''