The couple sued publishers of a magazine for defamation last year, but this much happier news. Photo: AAP

Justin Timberlake has taken to Instagram on his 34th birthday to announce he and wife Jessica Biel are expecting their first child.

“Thank you EVERYONE for the Bday wishes! This year, I’m getting the GREATEST GIFT EVER. CAN’T WAIT. #BoyOrGirl #YouNeverKnow #WeDontEvenKnow #WeAreTakingBets,” Timberlake wrote on his Instagram account on Saturday below a photograph of him kissing Biel’s pregnant belly.

Timberlake made his start as a child television star before joining ‘NSync.

More recently he has become one of the music industry’s most popular solo singers and starred in movies including the Facebook-themed drama The Social Network.

Timberlake married Biel, 32, in 2012.

Justin Timberlake Confirms Jessica Biel’s Pregnancy With the Sweetest Photo http://t.co/v16ZP2GkX5 pic.twitter.com/0BC86IPBQP

— Cosmopolitan (@Cosmopolitan) February 1, 2015