The music icon surprised his fans with a special, impromptu appearance.

Sir Elton John hosted a surprise, free concert in the Los Angeles gayborhood of Sunset Strip on Saturday afternoon.

The Grammy-winning entertainer performed for more than an hour – playing several tracks from his new album, Wonderful Crazy Night, including “Looking Up.”

However, in case an unexpected, free, full-length concert wasn’t enough of a treat, he then brought fellow Grammy-winner Lady Gaga onto stage for a stirring rendition of “Don’t Let the Sun Go Down on Me” and “Saturday Night’s Alright (For Fighting).”

John dedicated “Don’t Let the Sun Go Down on Me” to “all of you out there, for many years of love and loyalty.”

The star went on to dazzle at his post-annual Oscars bash that benefits his AIDS Foundation.

This year, the 24th annual party raised a whopping $6.2 million and had a host of celebrity guests, including Mariah Carey, Hilary Swank, Caitlyn Jenner and Sheryl Crow.

“By supporting our work, you are standing up against the issues that drive the AIDS epidemic,” John told his A-List guests.

“You are speaking out against racism, helping to end poverty and homelessness, and rejecting homophobia.

“By being here tonight, you are saying no to stigma, no to the status quo, and yes to a more just and equal society and the end of AIDS,” he added.

Something the Oscar winner failed to mention was Sam Smith’s cringe-worthy speech, in which he mistakenly claimed to be the first gay winner of the award.

Not only have a whole host of out gay people scooped an Oscar previously – John won the exact same award in 1994 for Can You Feel The Love Tonight.

However, in the build up to this year’s awards, Sir Elton did find time to lash out at fellow musician Janet Jackson, as he accused her of lip-syncing throughout her live shows.

“You know, fucking music magazines writing a review of Janet Jackson saying, ‘This is the greatest show – four and a half stars.’

“It’s fucking lip-synced! Hello! That’s not a show! I’d rather go and see a drag queen. Fuck off,” he said.

Watch him perform with Gaga below: