Kelly Clarkson delighted fans with covers of "Stay" and "Bye Bye Bye" in concert this week.

The 33-year-old "American Idol" winner performed the Rihanna song Sunday in Pittsburgh, Pa., and the 'N Sync hit Tuesday in Buffalo, N.Y. Clarkson also made headlines after covering Nick Jonas single "Jealous" last week in New York, N.Y.

"This is a throwback to our junior high days, and a lot of people in our crew are very excited about this," the star said before singing "Bye Bye Bye."

The song was released in January 2000, and is the lead single from 'N Sync's second album, No Strings Attached.

Clarkson recently explained the covers to Entertainment Weekly, saying, "We do a fan request every show, letting someone in the audience pick a song for us to cover.

It's a lot of fun for me and the band because the shows can become monotonous, and this keeps us on our toes."

Clarkson kicked off her Piece by Piece tour July 11 in Hershey, Pa.

The tour is in support of her album of the same name, and will come to a close Oct. 17 in Vancouver, B.C. The singer has previously covered Tracy Chapman song "Give Me One Reason."