When Jacob O'Connor found two-year-old Dylan floating face-down in the swimming pool he didn't rush off and find a grown up to help, instead he remembered a move from one of his favourite films, San Andreas.
Jacob, from Roseville, Michigan, managed to pull his brother out of the pool and started giving him chest compressions - just as he'd seen The Rock doing in the film.
Dylan was then rushed to hospital and went on to make a full recovery.
When he heard of Jacob's amazing intervention, Dwayne Johnson tweeted: "Wow amazing story....You're a real life hero. We're all proud of you! DJ".
Jacob's mother Christa O'Connor told the BBC: "I'm at a loss for words. I'm amazed at what Jacob did. I'm so proud of him."
She said her son was taking all the praise in his stride and added: "He just thinks it was the natural thing to do.
"Someone asked him if he thought he was a hero and he just said 'I don't know'.
"I'm surprised Jacob remembered what he'd seen in the film but it's one of his favourites and he'd seen it the week before."
The specific scene Jacob was copying was one in San Andreas where Johnson's character tries to save his on screen daughter.
Jacob told local news media: "I was scared when I saw Dylan in the pool."
"My favourite movie, San Andreas, had compressions (CPR) in the movie and I remembered it from the part in the movie where there was an earthquake, then there was a tsunami, and the girl was drowning.
"In most movies, that's what they do. They try to save the person first, and if it's not working, they go get someone."
The boys along with their other brother Gavin, 8, were being looked after by their grandmother while their mother was at work, but Dylan managed to somehow get out unnoticed.
When Jacob spotted his brother was gone he went to investigate and found he'd managed to unlock two back doors to get into the garden and then walk around the corner to the swimming pool.
After Jacob's life-saving resuscitation Dylan coughed up some water but because he didn't respond fully Jacob ran to tell his grandmother.
She called an ambulance and Dylan was rushed to hospital. In the meantime his mother drove frantically from work to meet them there.
"He was unconscious and on oxygen when I got there," she said, "and was kept in for two days.
"But he's well now and has no neurological damage or any lasting effects."
After all the trauma the mother-of-three can reflect positively on the accident, which happened at the end of last month.
"Thankfully we've been so lucky and it's like it never happened," she said.