In a crowd-pleasing mix of reggae and R&B, Grammy-winning singer Alicia Keys and opener Stephen Marley brought down the house at the Marcus Amphitheatre Tuesday night as Summerfest reached its midpoint.

Keys appeared onstage in true diva fashion and captivated in curve-hugging black pants and a leather vest, beginning with several upbeat songs from her latest album, "As I Am."

She then took to the piano to show off her instrumental talent and soulful voice on "Diary," "How Come You Don't Call Me Anymore" and "Like You'll Never See Me Again."

It seems wonderfully appropriate that a woman named Keys displays such an effortless dexterity on the piano. A classically trained pianist, the New York native blurs the lines between pop, R&B, hip-hop and soul.

In a perfect mix of uptempo and slow, and old and new songs, the performances of "A Woman's Worth" and "Fallin'," the signature hit that solidified her stardom in 2003, especially stood out. Keys then proceeded to nail favorites "Karma," "Unbreakable" and "You Don't Know My Name." She closed with the ubiquitous "No One."

At 27 years old and with nine Grammys under her belt, the multi-talented Keys is a role model worthy of praise. She has launched "Alicia in Africa," a documentary about the work of Keep a Child Alive and she is "Global Ambassador" for the organization. The multi-talented Keys also appeared in two films -- "The Nanny Diaries" and "Smokin' Aces" -- and is in the upcoming movie "The Secret Life of Bees."

Her encore performance of "If I Ain't Got You," from her second album, "The Diary of Alicia Keys," was a gracious thank you to her fans and a wonderful way to end the concert.

Stephen Marley, son of the legendary Bob Marley, opened the concert and performed reggae classics from his father's repertoire such as "Buffalo Soldier," "Get Up, Stand Up" and "Could You Be Loved." If you squinted, you would have sworn it was Bob himself on stage.

Marley has been in the spotlight from a very early age when, beginning in the late 1970s, he was co-lead singer of the Melody Makers with his brother Ziggy and sisters Sharon and Cedella. As the group's career progressed, Ziggy moved into the limelight and Stephen stepped back somewhat.

Now based in Miami, Marley has produced records by his brothers Damien (who dueted with Keys on her "Unplugged" disc in 2005) and Julian, and his own solo debut arrived in March 2007. "Mind Control" spawned the hit "Traffic Jam" and earned Marley the Grammy Award for Best Reggae Album.

For a moment the grassy hill behind the reserved seating in the Amphitheater was sand and the murky waters of Lake Michigan were crystal blue and salty. Marley's deep, raspy vocals and uplifting songs transported the crowd to Jamaica.

He was joined on stage by members of his entourage waving the Rasta flag, an adorable toddler pretending to play with the band and two female vocalists that carried a phenomenal rendition of "No Woman, No Cry."