Kirk Douglas. Picture: Supplied

Kirk Douglas's son Michael Douglas flew from New York to Beverly Hills to see his father on his 101st birthday over the weekend.

The 'Spartacus' star's son Michael Douglas flew from New York to Beverly Hills to see his father on his special day on Saturday, but his wife Catherine Zeta-Jones was unable to visit so had to video call him instead.

According to Deadline, the 48-year-old actress sang an Oscar-worthy rendition of 'Happy Birthday' to her father-in-law via FaceTime. 

Kirk's son Joel also attended the bash as did his wife Anne - who he has been married to since 1954 - and granddaughter Kelsey Douglas, 25. 

Following the event, Michael was due to fly back to the Big Apple because the arrival of his son's baby daughter is imminent. 

In April, Michael, 73, said he feels "fortunate" his father is still alive and admitted he was still "sharp". 

He said: "He's a pistol. When I come out here, I stay at my dad's house. He's got a little apartment above the garage. 

"I cherish the fact of how fortunate I am at my age that my dad's still around. 

"He's gonna be 101 in December, he's still sharp, got a good sense of humour and can share deep stories that go beyond being father and son.

"He's a lot better when my wife's out here - he seems to perk up when Catherine's around. He says, 'Oh, my goodness, look at you, you little rascal.' "

But Michael admitted Hollywood acting legend Kirk - who also starred in the likes of 'Paths of Glory' and 'Lust for Life' - does feel "lonely" at times because so many of his pals pass away. 

He added: "It's been a difficult time [for my father] right now - when you get to that age, you don't have many friends left, you know? It's a little more lonely."