Carrie Underwood detailed her pregnancy and announced a new single Friday.

The 31-year-old singer and husband Mike Fisher are expecting their first child, and shared the news September 1 on Instagram. Underwood told Today she and Fisher are excited to be parents, but said the experience is sometimes unreal.

"It's still kind of weird, to be honest," she admitted. "Sometimes with my husband, I'm like, 'I'm going to be a mom... you're going to be a dad... is this real life?' But we're really excited."

"I have a wonderful mother," she lauded. "So if I can be even a little bit like that, I think we'll be good."

Underwood also revealed she has a new single and greatest hits album in the works. The new single will be released Monday, and will appear on her first greatest hits album, Greatest Hits: Decade #1.

"The song is called 'Something in the Water,'" she announced. "It's a joyous, uplifting song about changing your life for the better and kind of having that 'A-ha!' moment, to waking up and your life being different from that moment forward."

Greatest Hits: Decade #1 will debut December 9. The singer last released Blown Away in 2012.