Justin Timberlake confirms wife Jessica Biel's pregnancy with cute pic

April 23, 2013. Justin Timberlake and wife, actress Jessica Biel, attend the TIME 100 Gala in New York. (The Associated Press)

It's Justin Timberlake's birthday, but it's another birth date that's on his mind — that of his future son or daughter.

The superstar shared a picture of a bulging belly — presumably belonging to wife Jessica Biel — on Instagram on Saturday, his 34th birthday. He wrote that he was getting the greatest gift ever this year and added: "CAN'T WAIT."

The sex of the baby is not yet known; the actor-singer joked that the couple is taking bets.

The Grammy-winning Timberlake married Biel in 2012. It will be the first child for both. Biel's pregnancy has been rumored for weeks but Timberlake's post is the first official confirmation.