Elton John, Lady Gaga throw surprise, free concert ahead of Oscars

On the eve of the Oscars, Elton John treated thousands of fans in Los Angeles to a surprise concert, and he did it for a simple but fitting reason: to say thank you.

The singer shut down a portion of the Sunset Strip on Saturday, along with special guest Lady Gaga, for the free performance. During the concert, he thanked the city of West Hollywood for supporting his Oscars viewing party, which raises money for the Elton John AIDS Foundation.

Lady Gaga, who is nominated for Best Original Song for "Til It Happens to You" from The Hunting Ground, joined John onstage for "Don't Let the Sun Go Down on Me." He also treated fans to hits like "Saturday Night's Alright" and new music like "Looking Up."

The Associated Press contributed to this report.

Watch the Oscars this Sunday on ABC! Live red carpet coverage begins at 5 p.m. ET | 4 p.m. CT | 2 p.m. PT with "ON THE RED CARPET AT THE OSCARS." Check your local listings.