Michael Bublé's wife organised a surprise circus-themed party for her husband's 40th birthday.

The singer - whose actual birthday isn't until September 9 - was thrown an unexpected bash by his pregnant wife, Argentine actress Luisana Lopilato, in Vancouver, Canada.

An insider told the New York Post newspaper: ''Michael was completely blown away.''

Luisana, 28, invited the singer's Canadian family as well as their closest friends, who flew from LA for the fancy party, which featured popcorn and cotton candy.

The 'Everything' singer later took to his Instagram account to post a picture of the party and to reveal his surprise.

He captioned the image: ''Tonight my wife Luisana Lopilato and my family surprised me with an amazing EARLY 40th bday paataay !! #39 #family (sic).''

Last month, Michael and his wife announced they are expecting their second child.

The couple - whose son Noah turns two later this month - revealed the news in a sweet video posted on Michael's Facebook page.

The clip features a soundtrack of Britney Spears' song 'Oops I did it again' and shows Noah point to his mother's stomach and say ''baby'' after Michael asks him ''who's in there?''