Way to go daddy!!!! #usa #rio2016 #pantsonfleek

A photo posted by boomer phelps (@boomerrphelps) on

Boomer wins best dressed! Michael Phelps may be racking up gold and making history on the daily, but his son is the one who's stealing the show. The athlete's baby boy, Boomer Phelps, wore an adorable shirt to cheer on his famous dad during the Rio Olympics on Wednesday, August 10.

"Way to go daddy!!!!" a photo caption read on the little guy's official Instagram account. "#usa #rio2016 #pantsonfleek."

In the pic, the 3-month-old smiles big for the camera. He's decked out in a "Team Daddy" T-shirt, patriotic-themed shorts and gold slippers.

Phelps and his fiancée, Nicole Johnson, shared another snapshot of their son on Thursday. "Today's a long day for daddy so I thought I'd catch a few extra!!" the caption read. "#babyneedhissleep."

Johnson, 31, and Boomer have been supporting the swimmer all week in Brazil. The family of three was captured hugging on TV Tuesday after Phelps won in the 200-meter butterfly and 4x200-meter freestyle relay, earning him his 20th and 21st gold medals.

Phelps opened up about fatherhood during a pretrials news conference in June. "It's still crazy. When I'm holding him or laying on the couch with him, it's just awesome. … I've learned which cry means what, if he needs a diaper change, if he needs mom, all of these different cries," he said via USA Today.

Today's a long for daddy so I thought I'd catch a few extra 💤 !! #babyneedhissleep

A photo posted by boomer phelps (@boomerrphelps) on

"It's been a really fun journey over the last couple of years, and a journey that I think has made me the person who I am and helped me transform to me just being me," he added of his relationship. "Nicole and I are so stoked."

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