Johnson, a Canadian international who captains the Portland Timbers, and Bradley, an American star who plays for Toronto FC, played together as kids in the Chicago area.
"I've lost track of the number of years, to be honest with you," the 27-year-old Johnson said of their friendship. "We grew up in Chicago playing youth soccer together a long long time ago.
"I was at his wedding and things like that so when we get an opportunity to be on a team like this together, it's special because when you're a 10-year-old boy just playing soccer on a random field, you never imagine this in your wildest dreams. So it's fun for us to share this experience."
Bradley's father Bob was coach of the Chicago Fire from 1998 to 2002.
Johnson, born in Toronto to English parents, moved to England as a baby and settled in the Chicago area at the age of 10.
Johnson says Bradley was special on the soccer field even as a pre-teen.
"He's always had the technique, always had the graft and the grind and hard work," said Johnson. "He's not that different from then than he is now ... He doesn't change. He does Michael. He was just as humble and hard-working back then as he is now."
Bradley says it doesn't take long to see how important Johnson is to his team.
"The way he's able, in the centre of the field, to take care of things ...get the ball and find the right guys."
As young pros, the two midfielders were also teammates at SC Heerenveen in the Netherlands.
Bradley, 27, says the two have remained close even when their careers have taken them far apart.
"He's a guy that I consider one of my closest friends," said Bradley. "To have the chance to spend a few days with him and be back on the same team is enjoyable for sure."
So did the two as kids ever dream of all-star moments?
"We probably did actually," said Bradley. "I'm not sure we had any reason to. But I think like all kids we dreamt big, that's for sure."
The MLS all-stars play German powerhouse Bayern Munich on Wednesday night at Providence Park.