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Michel Phelps, Boomer Phelps, Nicole Johnson

AP Photo/Mark J. Terrill

Michael Phelps' newborn baby boy is his biggest (and littlest) fan!

The Olympic swimmer's son, Boomer Phelps, sat in the stands on Tuesday, rooting his daddy on in the Olympic USA Swimming trials. 

Boomer's mama (and Phelps' fiancée), Nicole Johnson, held their 7-week-old child in her arms while dad competed in the 200-meter fly—which he ended up dominating, advancing him to compete for a spot on the 2016 Olympic team in the event.

Johnson—who held the title of Miss California USA in 2010—also took to Instagram to share a precious photo of Boomer wearing a "Team Daddy" shirt. "#teamdaddy all day err day!!" she captioned the pic with the pool in the background. "We LOVE you @m_phelps00 and we're cheering super loud for you!!"

Boomer even has his own Instagram account, which shared another photo from the big event. 

"Mom and I are excited to go watch dad tonight!!" the caption read, featuring Johnson holding Boomer in a sling across her chest. Mama donned her go-to "MP" shirt to rep her soon-to-be-hubby, while baby looked precious in a white and blue striped onesie.

The couple welcomed Boomer into the world on May 7, 2016. Phelps announced the happy news on his Instagram page, alongside a photo of him cradling his newborn son.

"Welcome Boomer Robert Phelps into the world!!!" he wrote. "Born 5-5-2016 at 7:21 pm !!! Healthy and happy!!!" He added, "Best feeling I have ever felt in my life!!! @nicole.m.johnson and Boomer both healthy!!! #boomerphelps."

Phelps and Johnson got engaged in February 2015 and announced her pregnancy nine months later, revealing they were expecting a baby boy.