Buzzy moments from the “A Decade of Difference” concert

The William J. Clinton Foundation's Decade of Difference Concert went off without a snag, no small feat given the number of surprises throughout the night.

Right off the bat, the concert got funky with surprise guest Stevie Wonder performing "Sir Duke" for the crowd at The Hollywood Bowl. The performance moved the famously weepy Clinton to tears (of happiness, we assume). Stevie spoke with the crowd and said Bill specifically requested his second tune, "For Once in My Life." Both President Clinton and Secretary of State Hillary Clinton were rocking out and grinning ear to ear, not the last time they'd be seen doing that during the night. Stevie closed with "Superstitious," a classic tune that he got the crowd to join in without much trouble.

After a performance by country superstar Kenny Chesney, Somalia-born hip hop star K'naan performed a set of songs, starting off with "Bullet Proof Pride." On the third verse he was joined by U2 frontman Bono. The crowd rose to its feet. Bono flashed a peace sign and left the stage (but he would return). K'naan raised the roof when he performed "Wavin' Flag," getting the crowd into it and shaking hands with the President and Secretary of State mid performance.

Following K'naan's set, actress Maria Bellow introduced Brazilian rocker Juanes, who rocked the stage and looked pretty darn cool while doing it.

Usher then took the stand and performed a trio of tracks, starting out with the Joe Cocker inspired version of The Beatles classic (and theme sone to "The Wonder Years") "With a Little Help From My Friends." It was a clear break from his usual type of tunes, but, not surprisingly, Usher pulled it off. The guy's a pro.

And then, just when you thought wardrobe malfunctions were a thing of the past, the R&B superstar accidentally split his pants down the left leg while singing "OMG." Not one to miss a beat, the singer had a smooth recovery, even making light of the unplanned split. He donned his shades, pointed to the growing hole, and said with a smile, "I work hard."