The Chicago actress took to the social media site to honour Kirk as he kicked off his big day.

"Happy Birthday Kirk, 100 years old today, love you pappy," she wrote at the beginning of the video, which included never-before-seen family footage and pictures of Kirk with the Welsh star and her husband, Michael Douglas.

It was Catherine's second post about the Spartacus legend this week - on Monday (05Dec16), in the lead up to his age milestone, she posted a black and white picture of a young Kirk with a female companion.

"A dashing Kirk Douglas, with a gorgeous girl in a gorgeous dress," she captioned the shot. "This is what we all should wear on a date. #MuseMonday."

Kirk's son Michael has planned a big birthday celebration for the star on Friday night, when around 200 guests have been invited to mark the occasion.

"About 200 friends and family members will be there, but that's about all I know," the birthday boy recently told Closer Weekly magazine. "My only job is to stay well and rested so I can show up and be charming. And, of course, give a little extemporaneous speech that I will have practised with my speech therapist, so people will understand me."

The Hollywood veteran, who suffered a stroke in 1996 which impaired his speech, is also planning a big gift to mark his 100th birthday, explaining he and his wife Anne "always use these happy occasions to give presents to the institutions we support through our foundation".

"Giving is a selfish act, I maintain, because it makes you feel so good," he added.