Avril Lavigne returns to stage

The "Complicated" hitmaker joined her ex-husband Chad Kroeger and his band Nickelback at their concert at the Greek Theatre in Los Angeles, California, to perform their song "Rockstar" along with a fan named Owen, who had been pulled out of the crowd by guitarist Ryan Peake, reported TMZ.

Nickelback tweeted post the show, "You never know who will join us for 'Rockstar' karaoke. And tonight we got super lucky with these two rockstars. It just might be you next!"

They later added in a post retweeted by Avril, "Any stage @AvrilLavigne graces is instantly better off for it. Blessed to have had her join us." Avril, 32, has stayed largely out of the spotlight over the last two years after contracting debilitating Lyme Disease, but has been working hard on her comeback. Avril hasn't released a new record since her 2013 self-titled fifth studio album, and in December the star revealed plans to drop music this year and admitted her fight against the disease will be reflected in the lyrics.