Michael Phelps: Wife Nicole expecting second child

Aug. 29 (UPI) -- Retired swimming superstar Michael Phelps and his wife Nicole are expecting baby No. 2.

The couple made the announcement Tuesday on mirrored social media posts.

"Number 2 on the way!!!! So excited!! Wonder if it's a boy or a girl??" Phelps wrote on Instagram. His post featured a photo of his wife with son Boomer. Phelps' post has more than 120,000 likes.

Boomer Phelps was born in May of 2016. The toddler has his own verified Instagram account with a respectable 795,000 followers.

"So excited to see what mama is having!! Do I get to have a brother or a sister?!?" a post from Boomer's account says. Boomer's post features the little boy excitedly clapping his hands and shows his mother's pregnancy test. The post has more than 44,000 likes on Instagram.

Michael and Nicole Phelps were married in June 2016 and again in October, according to People. Phelps owns 23 Olympic gold medals.

"Lil man's going to be a Big Brother!!!" Mrs. Phelps wrote on her account.

Phelps, 32, won a gold medal in his final race during the 4x100 medley relay at the Rio 2016 Summer Games. But all of his competitive spirit hasn't evaporated.

After tweeting during Floyd Mayweather's win Saturday against Conor McGregor, Phelps made a challenge to the Irishman.

"All of this talk...Should we race as well?? @TheNotoriousMMA," Phelps tweeted Tuesday.

McGregor has yet to get back to the seasoned swimming sensation.

Phelps is planning to serve as a volunteer assistant coach this fall for the Arizona State swim team.