That surprise was a guest appearance from Chris Brown.

In his first onstage appearance since pleading guilty to assaulting Rihanna in February, singer Chris Brown jumped onstage near the end of headliner Lil Wayne’s set. Brown, who is from Virginia, helped out by lending his voice to Drake’s “Every Girl,”[click here for the video] and paid tribute to Michael Jackson by moonwalking as “Billie Jean” played [click here for the video] in the background at the end of the night’s show. Wayne asked the crowd to make noise for “the new Michael.”

When asked by MTV News for a comment about the performance, Weezy responded simply via e-mail through a rep: “U kno I had to show him sum luv.”

The surprise appearance at the Young Money gig was Brown’s first public appearance since releasing a video on July 20 in which he apologized to Rihanna for the assault on the eve of the Grammys, which left her with facial contusions and cuts. Brown pleaded guilty last month to one count of felony assault and was ordered to perform 180 days of community service in Virginia as part of his plea deal.

Right now we’re not sure if Brown will be performing on other dates on the tour,which is scheduled to last through August 23. Brown appeared to be trying to fill a gap created when Drake went down on Friday night at a show in Camden, New Jersey, where he re-injured his already torn up knee, [click here for video] requiring immediate surgery. Drake blogged about being laid up over the weekend.