ST. PAUL — Stevie Wonder and Chaka Khan had the crowd partying like it was 1999 all over again at a tribute concert to Prince, nearly six months after his death.

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.”