B.o.B is certainly on a roll right now, with the #1 album in the country this week and its lead single "Nothin' on You" also a #1 hit. But the upstart hip-hop star, powered by his syrupy smash, almost didn't get his hands on the Bruno Mars-assisted "Nothin' on You."

The record, produced by the Smeezingtons (Bruno Mars and songwriting partner Phillip Lawrence), was originally slated for Lupe Fiasco, B.o.B's Atlantic Records labelmate. According to producer Jim Jonsin, who signed B.o.B to his Rebel Rock imprint, he was responsible for redirecting the record to his artist.

"I was actually working on a session in Chung King [Studios], and [Atlantic Records chairman] Craig Kallman called me during that session with that particular track, to work on it for Lupe Fiasco," Jonsin told MTV News. "I told Craig, 'I like the song a lot. It's a smash and could be somebody's single. But it's not Lupe's record. I need this record for B.o.B. Please give this record to B.o.B.' I guess they went through whoever they went through, convinced whoever they needed to, and it got to B.o.B."

As the song was climbing to the top of the Billboard Hot 100, B.o.B said he was as surprised as anyone by the song's success.

"We really didn't expect it to have the dramatic impact it had, nor how fast it happened," B.o.B told MTV News last month. "Me and my managers, B. Rich and TJ, we still look at each other speechless. We always aim to be successful. But when the byproduct exceeds your expectations — when usually you barely make the basket with what you want — the gratitude is through the roof. It's literally a dream come true."

The rewards have been a long time coming for the Atlanta rapper. He's been signed as an artist for a few years but realized only minimal success with a few scattered mixtape tracks. His potential, however, was always recognized, landing him on the 2009 cover of hip-hop magazine XXL's Freshmen 10 issue (putting him in the company of Wale and Asher Roth, among other rising MCs).

"I will tell you this about the journey as an artist to get to the point where you actually have a release date," he explained earlier this year. "The biggest lesson I learned is patience. Once you get here, it's like, 'OK, now you have to keep going. You never get to an end.' So you have to be patient and pace yourself. Take time. It's like building a house. You gotta take time, build a foundation, get the walls right, get the electricity right, get the plumbing right and make sure when you turn the light on that the door don't open up."

How do you think Lupe's "Nothin' on You" would have sounded? Share your thoughts in the comments!