Arnold Schwarzenegger threw a star-studded 68th birthday party yesterday (31.07.15).

The 'Terminator' actor celebrated hitting the milestone by gathering his friends and family together for the bash and even had a punching competition with his 'The Expendables' co-star Sylvester Stallone who claimed the former bodybuilder is ''getting stronger'' as he ages.

He tweeted: ''At Arnold's birthday party getting punched out. The man's not getting older, he's getting stronger!''

Sylvester, 69, also shared a photo of himself with Sir Elton John at the function, gushing the musician is one of his ''oldest friends''.

He wrote: ''Elton is one of my oldest friends! heart as big as a continent! A legend. (sic)''

Meanwhile, Arnold - who has kids Katherine, 25, Christina, 24, Patrick, 21 and Christopher, 17, with his ex-wife Maria Shriver, as well as 17-year-old Joseph Baena with his former employee Mildred Patricia Baena - had also marked the occasion on Thursday (30.07.15) by having a family lunch in Beverly Hills with his two daughters and Maria, who filed for divorce from him in 2011.

And in a video message posted on Twitter, he thanked his friends, family and fans for all of their kind wishes.

He said: ''I wanna say thank you to everybody for the birthday wishes. Thank you for the emails, and calling me and writing to me and all those kind of things. I'm having a the greatest time. My 68th birthday, wow. I'm in the gym working out, I went already on a motorcycle ride, on a bicycle ride, and now I'm going to have a little bit of lunch with my family. So hasta la vista and have a great time.''