Big Sean never wanted to rap on "My Last," the high-fructose Chris Brown collaboration that made Sean an urban radio star this year. But he certainly wanted to be a radio star - this is a guy who named three mixtapes and his debut album "Finally Famous" - so at the urging of producer No I.D., Sean went in.

Big Sean never wanted to rap on "My Last," the high-fructose Chris Brown collaboration that made Sean an urban radio star this year. But he certainly wanted to be a radio star - this is a guy who named three mixtapes and his debut album "Finally Famous" - so at the urging of producer No I.D., Sean went in.

Some folks call that selling out or going soft, but Sean, who just scored a second radio megahit with "Marvin & Chardonnay," sees it differently. You do what you have to do to get your foot in the door.

"Of course I didn't change," Sean said during a phone call this week. "You have to make music for yourself, for your believers and for the masses as well. That's who I want to be. I want to change the world. I want to be the voice of a nation."

If Sean, 23, had to go pop to get on the radio, he made his first power move on pure skills. As a high school student in urban Detroit, he regularly participated in a weekly rap battle at radio station 102.7 called Friday Night Cypher. In 2005, when Kanye West was at the station promoting his album "Late Registration," Sean stopped by the station and told the receptionist he had left his phone inside the night before.

The teenager found West, shook his hand and guilt-tripped the superstar into letting Sean rap 16 bars, the equivalent of one verse. To West's surprise, he ended up bobbing his head to Sean's lyrics.

"That 16 bars turned into 10 minutes," Sean said. "Everyone who worked at the station was clapping."

After a couple of years of sending music back and forth, West signed Big Sean to his G.O.O.D. Music label in 2007. That spawned the trilogy of "Finally Famous" mixtapes, appearances at high-profile concerts and a flurry of networking. One of his new celebrity connections, LeBron James, led to Sean guesting on "Poe'd Up," a track by rising Columbus rappers Fly.Union.

"Those are my homeys," Sean said. "I was really cool with LeBron James, and they had connections with him heavily. We all met up and were just kicking it, and I thought they were really cool guys."

Stylistically, the match made sense too: Fly.Union's Jerreau comes off like a more laid-back Jay-Z, while Sean raps with a sing-songy flow in the mold of his label boss, West. The track was a hit on the rap blogs - and perhaps they'll perform it Wednesday when Sean plays the Newport - but Sean has tapped into a much larger audience now. The talent that charmed Kanye six years ago has gone global.

"Just yesterday I had a realization when I was coming off the stage in Paris," Sean said. "Those people don't even speak English and they know every word to every song. That's the meaning of finally famous when you recognize you're doing something great. That can relate to anybody, man."