Stevie Wonder, Chaka Khan Headline Prince Tribute Show

Khan brought Wonder onstage Thursday night at Xcel Energy Center in St. Paul to duet on Prince’s “I Feel for You,” a 1984 hit for Khan. Wonder, wearing a suit and purple shirt, got the sold-out audience cheering with his signature harmonica riffs before the two performed Prince’s hit “1999,” with the crowd clapping and dancing along.

Just before show time, a concert publicist announced that singer Christina Aguilera canceled her scheduled appearance as she fights a “vocal illness.” Singer Jessie J replaced Aguilera in the lineup.

A representative for Aguilera said she “has been advised by her doctors not to perform due to a vocal illness she has been trying to shake all week.”

Pop star John Mayer bowed out of the concert earlier, citing a “change of schedule.” Singer Anita Baker canceled her appearance just before the event, but a publicist for the show did not know the reason.

On the outdoor plaza before the concert, fans wearing purple shirts, scarves and the occasional raspberry beret milled about and some danced. St. Paul Mayor Chris Coleman read a proclamation declaring Thursday Prince Day in Minnesota’s capital. President Barack Obama delivered a taped message as the concert opened.

Prince’s younger sister, Tyka Nelson, described the concert as a public memorial to the seven-time Grammy winner.

“I want them to get some closure,” Nelson said of Prince’s fans. “It takes time to kind of get over it, and I see that they are grief-stricken.” She said there “definitely” will be future concerts.

In an interview with The Associated Press, Khan said Prince’s funky, syncopated music is a “brand that’s going to live forever.”

“There’ll always be somebody that says, ‘Ooh, that sounds real Prince-like, you know what I’m saying? His name will come up throughout millennia,” Khan said.

Tori Kelly and Doug E. Fresh also were included in the lineup, along with Prince’s ex-wife Mayte Garcia, Morris Day & The Time, Judith Hill and Liv Warfield.

The Prince family-sanctioned concert originally was planned for the Minnesota Vikings’ new U.S. Bank Stadium in downtown Minneapolis, but was moved to the smaller Xcel Energy Center.

Prince’s family initially announced the concert in late July, but details did not emerge until September. Fans quickly snapped up tickets when they went on sale last month.

Prince died of an accidental painkiller overdose in April at his Paisley Park recording complex. The singer of hits including “Purple Rain,” ‘‘Let’s Go Crazy” and “The Most Beautiful Girl in the World” was 57.