Phelps son Boomer cracked a smile as his dad dominated the 200-meter butterfly at Tuesday's USA Swimming trials

Michael Phelps had a special supporter in the stands on Tuesday as he dominated at the USA Swimming trials — his son, Boomer Robert.

Phelps’ fiancée Nicole Johnson held the 7-week-old in her arms as Phelps focused on the 200-meter butterfly — and advanced to compete for a spot on the Olympic team in the event.

“#Teamdaddy all day err day!! We LOVE you @m_phelps00 and we’re cheering super loud for you!!” Johnson captioned an Instagram photo of the infant wearing a onesie with the words “team daddy” on it.

Michael Phelps son Boomer Olympic trials

Mark J. Terrill/AP

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Another photo of Johnson with Boomer was uploaded to the infant’s own Instagram earlier in the day. The caption read: “Mom and I are excited to go watch dad tonight!!”

Michael Phelps son Boomer Olympic trials

Mark J. Terrill/AP

The couple welcomed their first child on May 5, and Boomer made his debut in a sweet Instagram photo of the family in the hospital shortly after the birth.

“Welcome Boomer Robert Phelps into the world!!! Born 5-5-2016 at 7:21 pm !!! Healthy and happy!!! Best feeling I have ever felt in my life!!!” Phelps captioned the photo.

The two, both 30, announced the pregnancy in November and celebrated the upcoming birth with a cowboy-themed baby shower in March.

Phelps and the former Miss California have been dating on and off since 2007. The two split in 2011, but rekindled their romance in 2014 and became engaged in February.

— Char Adams