The Canadian crooner marks the milestone on 9 September (15), but his pregnant wife Luisana Lopilato decided to surprise him a month ahead of schedule by throwing him an early birthday bash in Vancouver.

The circus-themed party at The Permanent venue on Saturday (08Aug15) featured games, popcorn and cotton candy, as well as a light display which spelled out Buble's name and age.

Buble thanked his wife for her efforts by sharing a picture on showing the couple posing underneath the illuminated sign with the caption, "My wife Luisana Lopilato and my family surprised me with an amazing early 40th bday paataay (sic)!! #39 #family (sic)."