Jason Castro was shown the door on "American Idol" tonight after receiving the fewest votes from the show's viewers. Thus, four became three, as Sayesha Mercado and "the Davids" -- David Archuleta and

Jason Castro was shown the door on "American Idol" tonight (May 7) after receiving the fewest votes from the show's viewers. Thus, four became three, as Sayesha Mercado and "The Davids" -- David Archuleta and David Cook -- moved on in the finals.

The performance round on Tuesday focused on the songs of Rock and Roll Hall of Famers and the dreadlocked, guitar-wielding 20-year-old blanked on the lyrics of Bob Dylan's "Mr. Tambourine Man" after delivering Bob Marley's "I Shot the Sherriff." Prior to being booted, Castro was joined onstage by Mercado as the other contestant with the lowest vote count. Castro was grinning ear to ear as he exited re-hashing "Sherriff."

Special guests for the night included Maroon 5 tackling their latest single "If I Never See Your Face Again" and AI season four finalist Bo Bice performing "Witness," culled from his latest effort "See the Light."

Announced also were details on the American Idols Live tour, which kicks off July 1 in Glendale, Ariz., and runs through mid-September. Tickets go on sale May 17 for the stint, featuring the top 10 finalists from this season.

Next week, the remaining contestants are charged to perform three songs each.

To read Billboard.com's interview with all four of this week's finalists, click here.