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 Instagram.com 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)."