Nevin is guaranteed at least a bronze medal after his thrilling victory over Mexico’s Oscar Valdez Fierro on Sunday night.
The Cavan fighter made history as the first Irish Traveller to win an Olympic medal when he outpointed the Mexican 19-13.
He is now two fights away from a gold medal as boxing again flies the flag for Ireland at the Olympics.
And Nevin revealed to the Irish Sun after his latest win that his triumph is dedicated to the memory of his 25-year-old cousin who died tragically of a heart attack earlier this year.
David, who claimed two Ulster titles and fought for Ireland, had planned to support John Joe before tragedy struck in February.
Minutes after he secured the Olympic medal, Nevin told the Irish Sun: “David was meant to be here, my cousin David.
“I said it to the lads at his funeral - he had said to me, ‘you’ll go all the way, John Joe’.
“He was booking his tickets and all when the boys were booking theirs and he passed away. He would have fought under Billy Walsh our coach and them as well. He just took a heart attack out of the blue, he was only 25.”
Close to tears, Nevin added: “I take my hat off to him, it was the likes of him who inspired me in boxing and I’m very, very sad to talk about him now.
“I’d like to thank him though, it means a lot to me. I know he should have been here now but, as I said at his funeral, hopefully he is with me. I know he is there.”
World champion Lazaro Alvarez Estrado is next up for Nevin in the bantamweight semi-final on Friday but the Irishman is determined to turn his bronze medal into gold.
After surviving a put-down on Sunday night, he added: “It feels amazing. As I said from the start, to represent my country is a dream come true for me.
“I’d trade the two bronze medals at the world championships for an Olympic one but now I want to go all the way. As I said to the boys it’s like that Queen song - I want it all.
“I want every day of it. I want to be the best in the world. I take my hat off to anyone that’s able to beat me. They are the better man on the day.
“The next guy is world champion, but I’m going to relax and enjoy the day. That’ll be a story for another day and we’ll see what happens then.”