Don't expect to see much more of contestant Jason Castro on American Idol, says judge Simon Cowell.

The dreadlocked singer, 20, forgot the lyrics to Bob Dylan's "Mr. Tambourine Man" on Tuesday's show.

Snapped Cowell: "Jason, I'd pack your suitcase!"

Even Castro confessed, "I lost some lines in there - that's kinda' bad."

Acording to sources, Castro was "shaken up" while performing the Dylan tune because Cowell "had his hand over his face" and kept sighing when he performed his first number of the night, Bob Marley's "I Shot the Sheriff."

Meanwhile, contestant David Archuleta was the night's clear front-runner: He received glowing praises from all of the judges.