Willie Nelson celebrated his 72nd birthday Saturday (April 30) with a sold-out show under the stars at Los Angeles' famed Greek Theater. The concert included opening sets by Shelby Lynne and blues artist Susan Tedeschi as well as guest appearances by ZZ Top's Billy Gibbons and the Nitty Gritty Dirt Band's John McEuen. Nelson's Dukes of Hazzard co-star, Jessica Simpson, took the stage to join in a gospel medley before leading the crowd in a round of "Happy Birthday." Nelson also shared the spotlight with two of his sons, playing the part of proud dad while watching son Lucas provide lead vocals and guitar on "Texas Flood." Son Michael stayed more in the background alternating from drums to guitar. Dressed in a Hawaiian shirt and tennis shoes, Nelson was all smiles and in fine voice throughout the set. His recent bout with carpal tunnel syndrome is clearly under control, as Nelson handled several long guitar solos with his usual finesse.