Aretha Franklin has taken to the stage with former US secretary of state Condoleezza Rice to raise money for children in urban areas.
The rare duet with Condoleezza, a classically trained pianist, was also held to increase funds for music and the arts.
"It is a joint effort for the inner-city youth of Philadelphia and Detroit," Aretha said before their concert with the Philadelphia Orchestra in the city's Mann Music Centre.
Their appearance in the three-hour show, before a crowd of around 8,000, overflowed with Aretha's hits as well as arias from the world of opera and classical music.
"We decided to give it a try," Aretha said. "So here we are, in the city of Brotherly - and Sisterly - Love."
Condoleezza, better known as a diplomat and national security adviser, accompanied Aretha singing her hit I Say A Little Prayer as well as My Country 'Tis Of Thee.
Condoleezza said she rehearsed furiously for her performance of Mozart's Piano Concerto in D Minor with the orchestra.
Aretha's repertoire included songs from her new album A Woman Falling Out Of Love, to be released later this year.